Sulfonylurea-responsive repressor proteins

ABSTRACT

Compositions and methods relating to the use of sulfonylurea-responsive repressors are provided. Compositions include polypeptides that specifically bind to an operator, wherein the specific binding is regulated by a sulfonylurea compound. Compositions also include polynucleotides encoding the polypeptides as well as constructs, vectors, prokaryotic and eukaryotic cells, and eukaryotic organisms including plants and seeds comprising the polynucleotide, and/or produced by the methods. Also provided are methods to provide a sulfonylurea-responsive repressor to a cell or organism, and to regulate expression of a polynucleotide of interest in a cell or organism, including a plant or plant cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Application Ser. No. 61/108,917 filed Oct. 28, 2008, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to the field of molecular biology, more particularly to the regulation of gene expression.

BACKGROUND

The tetracycline operon system, comprising repressor and operator elements, was originally isolated from bacteria. The operon system is tightly controlled by the presence of tetracycline, and self-regulates the level of expression of tetA and tetR genes. The product of tetA removes tetracycline from the cell. The product of tetR is the repressor protein that binds to the operator elements with a K_(d) of about 10 pM in the absence of tetracycline, thereby blocking expression or tetA and tetR.

This system has been modified to control expression of other polynucleotides of interest, and/or for use in other organisms, mainly for use in animal systems. Tet operon based systems have had limited use in plants, at least partially due to problems with the inducers which are typically antibiotic compounds, and sensitive to light.

There is a need to regulate expression of sequences of interest in organisms, compositions and methods to tightly regulate expression in response to sulfonylurea compounds are provided.

SUMMARY

Compositions and methods relating to the use of sulfonylurea-responsive repressors are provided. Compositions include polypeptides that specifically bind to an operator, wherein the specific binding is regulated by a sulfonylurea compound. Compositions also include polynucleotides encoding the polypeptides as well as constructs, vectors, prokaryotic and eukaryotic cells and eukaryotic organisms including plants and seeds comprising the polynucleotide and/or produced by the methods. Also provided are methods to provide a sulfonylurea-responsive repressor to a cell or organism and to regulate expression of a polynucleotide of interest in a cell or organism, including a plant or plant cell.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1. Docking of tetracycline-Mg++ and the sulfonylurea compound Harmony® (thifensulfuron-methyl; Ts) into the binding pocket of class D TetR based on the crystal structure 1DU7 from the Protein Databank (PDB).

FIG. 2. Vector map of an exemplary E. coli-based tetR expression vector, pVER7314. The replicon backbone is based on that of pBR322. The TetR ligand binding domain (LBD) is encoded flanked by SacI and AscI sites. KMsp172 and KMsp173 represent binding sites for the primers used for DNA sequencing of inserted tetR genes. rrnB T1 T2 is a strong transcriptional terminator to inhibit run around transcription and unregulated tetR expression.

FIG. 3. Response of library 1 hits to 20 μg/ml thifensulfuron-methyl (Ts). E. coli KM3 cells harboring putative tetR hits L1-1 through L1-20 or wt tetR were replica plated onto M9 assay medium +/−20 μg/ml Ts, then incubated at 30° C. until blue/white colony discrimination was evident. At this time colonies were imaged and relative β-galactosidase activity determined based on degree of blue colony color.

FIG. 4. Relative β-galactosidase activities of 45 putative library L4 hits against 0, 0.2 and 1.0 ppm ethametsulfuron (Es). Induced activity was measured using 5 μl of perforated whole cell mixture, and background activity was measured using 25 μl perforated cell mixture so that detectable activity could be measured in the same time frame for all treatments. Background activity values were multiplied by 10 in order to bring them into the display range of the graph. The right hand side of the graph contains the controls, wild type TetR and 1^(st) round hit L1-9.

FIG. 5. β-galactosidase induction in L7 hits with ethametsulfuron. Top hits from the L7 library were re-arrayed and tested in 96-well culture format for relative induction by 0.02 μg/ml and 0.2 μg/ml inducer (Es), and for background activity in the absence of inducer. Induced activity was assayed using 5 μl of perforated cell mixture, whereas 25 μl of cells was used to detect background activity. This allowed all detectable activities to be measured in the same time frame for all treatments. Background activity values were multiplied by ten to bring them into the range of the graph. The latter part of the graph shows the controls: 2nd round hits L4-89 and L4-120, and wt TetR(B) with ethametsulfuron; and wt TetR with 0.4 μM atc as cognate inducer for comparison (diagonally striped bar). Well ID's indicated with slanted text refer to that of the assay re-array whereas original clone ID's are indicated below in horizontal text.

FIG. 6. Ethametsulfuron dose response of two EsR variants determined by transient expression in Nicotiana benthamiana leaves. Black bars represent wt TetR, grey bars represent EsR hit A11, and white bars represent EsR hit D01. The striped bar represents a no repressor control which indicates the maximum level of reporter expression in the assay.

FIG. 7. DNA binding to tetOp in the absence or presence of ligand. Five pmol TetO or control DNA was mixed with the indicated amounts of repressor protein and inducer in complex buffer containing 20 mM Tris-HCl (pH8.0) and 10 mM EDTA.

FIG. 8. Structures of exemplary registered sulfonylurea compounds.

FIG. 9. Summary of source diversity, library design, and hit diversity and population bias for several generations of sulfonylurea repressor shuffling libraries. A dash (“-”) indicates no amino acid diversity introduced at that position in that library. An X indicates that the library oligos were designed to introduce complete amino acid diversity (any of 20 amino acids) at that position in that library. Residues in bold indicate bias during selection with larger font size indicating a greater degree of bias in the selected population. Residues in parentheses indicate selected mutations. The phylogenetic diversity pool is derived from a broad family of 34 tetracycline repressor sequences.

FIG. 10. Sulfonylurea depression of fluorescent reporter in maize callus (A) or plants (B).

FIG. 11. β-galactosidase induction in exemplary L13 hits with ethametsulfuron.

DETAILED DESCRIPTION

Chemically regulated expression tools have proven valuable for studying gene function and regulation in many biological systems. These systems allow testing for the effect of expression of any gene of interest in a culture system or whole organism when the transgene cannot be specifically regulated, or continuously expressed due to negative consequences. These systems essentially provide the opportunity to do “pulse” or “pulse-chase” gene expression testing. A chemical switch-mediated expression system allows testing of genomic, proteomic, and/or metabolomic responses immediately following activation of the target gene. These types of tests cannot be done with constitutive, developmental, or tissue-specific expression systems. Chemical switch technologies may also provide a means for gene therapy.

Chemical switch systems can be commercially applied, such as in agricultural biotechnology. For agricultural purposes it is desired to be able to control the expression and/or genetic flow of transgenes in the environment, such as herbicide resistance genes, especially in cases where weedy relatives of the target crop exist. In addition, having a family of viable chemical switch mechanisms would enable trait inventory management from a single transgenic crop, for example, one production line could be used to deliver selected traits on customer demand via specific chemical activation. Additionally, hybrid seed production could be streamlined by using chemical control of hybrid maintenance.

The Tet repressor (TetR) based genetic switch system widely used in animal systems has had limited use in plant genetic systems, due in part to problems with the activator ligands. TetR has been redesigned to recognize commercially used sulfonylurea chemistry instead of tetracycline compounds, while retaining the ability to specifically bind tetracycline operator sequences. This was accomplished by modifying the Tet repressor ligand binding domain using rational protein modeling and DNA shuffling to recognize commercially used sulfonylurea compounds. Initial TetR shuffling and screening using a sensitive in vivo β-galactosidase assay led to specific recognition of the herbicide Harmony® (thifensulfuron-methyl) at 20 ppm in the growth medium, and loss of recognition of tetracycline. Upon testing with other sulfonylurea compounds, many of the hits reactive to Harmony® also responded to other SU compounds. In some cases, the hits had even better reactivity to related herbicides chlorsulfuron and ethametsulfuron (2 ppm). Further rounds of shuffling and screening of the TetR derivatives led to TetR variants that react robustly to 0.2 ppm chlorsulfuron and 0.02 ppm ethametsulfuron as measured using in vivo induction assays in E. coli. Top performing ethametsulfuron responsive SuR variants (EsRs) show induction capacity nearly equal to that of wild type class B TetR induction by anhydrotetracycline (atc) using similar inducer concentrations. These SuR molecules have no reactivity to tetracyclines, and wild type TetR(B) (SEQ ID NO: 2) has no reactivity to the sulfonylureas.

Compositions and methods relating to the use of sulfonylurea-responsive repressors are provided. Sulfonylurea-responsive repressors (SuRs) include any repressor polypeptide whose binding to an operator sequence is controlled by a ligand comprising a sulfonylurea compound. In some examples, the repressor binds specifically to the operator in the absence of a sulfonylurea ligand. In some examples, the repressor binds specifically to the operator in the presence of a sulfonylurea ligand. Repressors that bind to an operator in the presence of the ligand are sometimes called a reverse repressor. In some examples compositions include SuR polypeptides that specifically bind to a tetracycline operator, wherein the specific binding is regulated by a sulfonylurea compound. In some examples compositions include an isolated sulfonylurea repressor (SuR) polypeptide comprising at least one amino acid substitution to a wild type tetracycline repressor protein ligand binding domain wherein the SuR polypeptide, or a multimer thereof, specifically binds to a polynucleotide comprising an operator sequence, wherein repressor-operator binding is regulated by the absence or presence of a sulfonylurea compound. In some examples compositions included isolated sulfonylurea repressors comprising a ligand binding domain comprising at least one amino acid substitution to a wild type tetracycline repressor protein ligand binding domain fused to a heterologous operator DNA binding domain which specifically binds to a polynucleotide comprising the operator sequence or derivative thereof, wherein repressor-operator binding is regulated by the absence or presence of a sulfonylurea compound. Any operator DNA binding domain can be used, including but not limited to an operator DNA binding domain from repressors included tet, lac, trp, phd, arg, LexA, phiCh1 repressor, lambda C1 and Cro repressors, phage X repressor, MetJ, phir1t rro, phi434 C1 and Cro repressors, RafR, gal, ebg, uxuR, exuR, ROS, SinR, PurR, FruR, P22 C2, TetC, AcrR, Betl, Bm3R1, EnvR, QacR, MtrR, TcmR, Ttk, YbiH, YhgD, and mu Ner, or DNA binding domains in Interpro families including but not limited to IPR001647, IPR010982, and IPR011991.

In some examples compositions include an isolated sulfonylurea repressor (SuR) polypeptides comprising at least one amino acid substitution to a wild type tetracycline repressor protein wherein the SuR polypeptide, or a multimer thereof, specifically binds to a polynucleotide comprising a tetracycline operator sequence, wherein repressor-operator binding is regulated by the absence or presence of a sulfonylurea compound.

Wild type repressors include tetracycline class A, B, C, D, E, G, H, J and Z repressors. An example of the TetR(A) class is found on the Tn1721 transposon and deposited under GenBank accession X61307, crossreferenced under gi48198, with encoded protein accession CAA43639, crossreferenced under gi48195 and UniProt accession Q56321. An example of the TetR(B) class is found on the Tn10 transposon and deposited under GenBank accession X00694, crossreferenced under gi43052, with encoded protein accession CAA25291, crossreferenced under gi43052 and UniProt accession P04483. An example of the TetR(C) class is found on the pSC101 plasmid and deposited under GenBank Accession M36272, crossreferenced under gi150945, with encoded protein accession AAA25677, crossreferenced under gi150946. An example of the TetR(D) class is found in Salmonella ordonez and deposited under GenBank Accession X65876, crossreferenced under gi49073, with encoded protein accession CAA46707, crossreferenced under gi49075 and UniProt accessions P0ACT5 and P09164. An example of the TetR(E) class was isolated from E. coli transposon Tn10 and deposited under GenBank Accession M34933, crossreferenced under gi155019, with encoded protein accession AAA98409, crossreferenced under gi155020. An example of the TetR(G) class was isolated from Vibrio anguillarium and deposited under GenBank Accession S52438, crossreferenced under gi262928, with encoded protein accession AAB24797, crossreferenced under gi262929. An example of the TetR(H) class is found on plasmid pMV111 isolated from Pasteurella multocida and deposited under GenBank Accession U00792, crossreferenced under gi392871, with encoded protein accession AAC43249, crossreferenced under gi392872. An example of the TetR(J) class was isolated from Proteus mirabilis and deposited under GenBank Accession AF038993, crossreferenced under gi4104704, with encoded protein accession AAD12754, crossreferenced under gi4104706. An example of the TetR(Z) class was found on plasmid pAGI isolated from Corynebacterium glutamicum and deposited under GenBank Accession AF121000, crossreferenced under gi4583389, with encoded protein accession AAD25064, crossreferenced under gi4583390. In some examples the wild type tetracycline repressor is a class B tetracycline repressor protein. In some examples the wild type tetracycline repressor is a class D tetracycline repressor protein.

In some examples the sulfonylurea repressor (SuR) polypeptides comprise an amino acid substitution in the ligand binding domain of a wild type tetracycline repressor protein. In class B and D wild type TetR proteins, amino acid residues 6-52 represent the DNA binding domain. The remainder of the protein is involved in ligand binding and subsequent allosteric modification. For class B TetR residues 53-207 represent the ligand binding domain, while residues 53-218 comprise the ligand binding domain for the class D TetR. In some examples the SuR polypeptides comprise an amino acid substitution in the ligand binding domain of a wild type TetR(B) protein. In some examples the SuR polypeptides comprise an amino acid substitution in the ligand binding domain of a wild type TetR(B) protein of SEQ ID NO: 1.

In some examples the isolated SuR polypeptides comprise an amino acid, or any combination of amino acids, corresponding to equivalent amino acid positions selected from the amino acid diversity shown in FIG. 9, wherein the amino acid residue position shown in FIG. 9 corresponds to the amino acid numbering of a wild type TetR(B). In some examples the isolated SuR polypeptides comprise a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues shown in FIG. 9, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of a wild type TetR(B). In some examples the isolated SuR polypeptides comprise at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues shown in FIG. 9, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of a wild type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated SuR polypeptide comprises a ligand binding domain comprising an amino acid substitution at a residue position selected from the group consisting of position 55, 60, 64, 67, 82, 86, 100, 104, 105, 108, 113, 116, 134, 135, 138, 139, 147, 151, 170, 173, 174, 177 and any combination thereof, wherein the amino acid residue position and substitution corresponds to the equivalent position using the amino acid numbering of a wild type TetR(B). In some examples the isolated SuR polypeptide further comprises an amino acid substitution at a residue position selected from the group consisting of 109, 112, 117, 131, 137, 140, 164 and any combination thereof. In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated SuR polypeptides comprise a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues selected from the group consisting of:

(a) M or L at amino acid residue position 55;

(b) A, L or M at amino acid residue position 60;

(c) A, N, Q, L or H at amino acid residue position 64;

(d) M, I, L, V, F or Y at amino acid residue position 67;

(e) N, S or T at amino acid residue position 82;

(f) F, M, W or Y at amino acid residue position 86;

(g) C, V, L, M, F, W or Y at amino acid residue position 100;

(h) R, A or G at amino acid residue position 104

(i) A, I, V, F or W at amino acid residue position 105;

(j) Q or K at amino acid residue position 108;

(k) A, M, H, K, T, P or V at amino acid residue position 113;

(l) I, L, M, V, R, S, N, P or Q at amino acid residue position 116;

(m) I, L, V, M, R, S or W at amino acid residue position 134;

(n) R, S, N, Q, K or A at amino acid residue position 135;

(o) A, C, G, H, I, V, R or Tat amino acid residue position 138;

(p) A, G, I, V, M, W, N, R or Tat amino acid residue position 139;

(q) I, L, V, F, W, T, S or R at amino acid residue position 147;

(r) M, L, W, Y, K, R or S at amino acid residue position 151;

(s) I, L, V or A at amino acid residue position 170;

(t) A, G or V at amino acid residue position 173;

(u) L, V, W, Y, H, R, K or S at amino acid residue position 174; and,

(v) A, G, I, L, Y, K, Q or Sat amino acid residue position 177,

wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the isolated SuR polypeptides comprise at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the amino acid residues listed in (a)-(v) above, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated SuR polypeptides selected for enhanced activity on chlorsulfuron comprise a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the group consisting of:

(a) M at amino acid residue position 60;

(b) A or Q at amino acid residue position 64;

(c) M, F, Y, I, V or L at amino acid residue position 67;

(d) N or T at amino acid residue position 82;

(e) M at amino acid residue position 86;

(f) C or W at amino acid residue position 100;

(g) W at amino acid residue position 105;

(h) Q or K at amino acid residue position 108;

(i) M, Q, L or H at amino acid residue position 109;

(j) G, A, S or T at amino acid residue position 112;

(k) A at amino acid residue position 113;

(l) M or Q at amino acid residue position 116;

(m) M or V at amino acid residue position 134;

(n) G or R at amino acid residue position 138;

(o) N or V at amino acid residue position 139;

(p) F at amino acid residue position 147;

(q) S or L at amino acid residue position 151;

(r) A at amino acid residue position 164;

(s) A, L or V at amino acid residue position 170;

(t) A, G or V at amino acid residue position 173;

(u) L or W at amino acid residue position 174; and;

(v) K at amino acid residue position 177,

wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the isolated SuR polypeptides comprise at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the amino acid residues listed in (a)-(v) above, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated SuR polypeptides selected for enhanced activity on ethametsulfuron comprise a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% the amino acid residues are selected from the group consisting of:

(a) M or L at amino acid residue position 55;

(b) A at amino acid residue position 64;

(c) M, Y, F, I, L or V at amino acid residue position 67;

(d) M at amino acid residue position 86;

(e) Cat amino acid residue position 100;

(f) G at amino acid residue position 104;

(g) F at amino acid residue position 105;

(h) Q or K at amino acid residue position 108;

(i) Q, M, L or H at amino acid residue position 109;

(j) S, T, G or A at amino acid residue position 112;

(k) A at amino acid residue position 113;

(l) S at amino acid residue position 116;

(m) M or L at amino acid residue position 117;

(n) M or L at amino acid residue position 131;

(o) M at amino acid residue position 134;

(p) Q at amino acid residue position 135;

(q) A or V at amino acid residue position 137;

(r) C or G at amino acid residue position 138;

(s) I at amino acid residue position 139;

(t) F or Y at amino acid residue position 140;

(u) L at amino acid residue position 147;

(v) L at amino acid residue position 151;

(w) A at amino acid residue position 164;

(x) V, A or L at amino acid residue position 170;

(y) G, A or V at amino acid residue position 173

(z) L at amino acid residue position 174; and,

(aa) N or K at amino acid residue position 177,

wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the isolated SuR polypeptides comprise at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% the amino acid residues are selected from the amino acid residues listed in (a)-(aa) above, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated SuR polypeptide has at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to the ligand binding domain of a wild type TetR(B) exemplified by amino acid residues 53-207 of SEQ ID NO: 1, wherein the sequence identity is determined over the full length of the ligand binding domain using a global alignment method. In some examples the global alignment method uses the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

In some examples the isolated SuR polypeptide has at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to a wild type TetR(B) exemplified by SEQ ID NO: 1, wherein the sequence identity is determined over the full length of the polypeptide using a global alignment method. In some examples the global alignment method uses the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

Compositions include isolated SuR polypeptides having at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to the ligand binding domain of an SuR polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243, wherein the sequence identity is determined over the full length of the ligand binding domain using a global alignment method. In some examples the global alignment method uses the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

In some examples the isolated SuR polypeptide have at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to an SuR polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243, wherein the sequence identity is determined over the full length of the polypeptide using a global alignment method. In some examples the global alignment method uses the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST bit score of at least 374, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a percent sequence identity of at least 88% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST bit score of at least 387, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a percent sequence identity of at least 92% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST bit score of at least 393, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST similarity score of at least 1006, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST e-value score of at least e-112, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST bit score of at least 388, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST similarity score of at least 996, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST e-value score of at least e-111, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST e-value score of at least e-111, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST bit score of at least 381, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST similarity score of at least 978 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST e-value score of at least e-108, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a percent sequence identity of at least 90% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST bit score of at least 368, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST similarity score of at least 945 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST e-value score of at least e-105, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a percent sequence identity of at least 86% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST bit score of at least 320, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a percent sequence identity of at least 86% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST similarity score of at least 819 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the SuR polypeptides comprise an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST e-value score of at least e-90, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243.

In some examples the isolated SuR polypeptides comprise a ligand binding domain from a polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated SuR polypeptides comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated SuR polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243, and the sulfonylurea compound is selected from the group consisting of a chlorsulfuron, an ethametsulfuron, a metsulfuron, a sulfometuron, a tribenuron, a chlorimuron, a nicosulfuron, a rimsulfuron and a thifensulfuron.

In some examples the isolated SuR polypeptides have an equilibrium binding constant for a sulfonylurea compound greater than 0.1 nM and less than 10 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound of at least 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM but less than 10 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound of at least 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM but less than 1 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound greater than 0 nM, but less than 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM or 10 μM. In some examples the sulfonylurea compound is a chlorsulfuron, an ethametsulfuron, a metsulfuron, a sulfometuron, a tribenuron, a chlorimuron, a nicosulfuron, a rimsulfuron and/or a thifensulfuron.

In some examples the isolated SuR polypeptides have an equilibrium binding constant for an operator sequence greater than 0.1 nM and less than 10 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for an operator sequence of at least 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM but less than 10 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for an operator sequence of at least 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM but less than 1 μM. In some examples the isolated SuR polypeptide has an equilibrium binding constant for an operator sequence greater than 0 nM, but less than 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM or 10 μM. In some examples the operator sequence is a Tet operator sequence. In some examples the Tet operator sequence is a TetR(A) operator sequence, a TetR(B) operator sequence, a TetR(D) operator sequence, TetR(E) operator sequence, a TetR(H) operator sequence, or a functional derivative thereof.

The isolated SuR polypeptides specifically bind to a sulfonylurea compound. Sulfonylurea molecules comprise a sulfonylurea moiety (—S(O)2NHC(O)NH(R)—). In sulfonylurea herbicides the sulfonyl end of the sulfonylurea moiety is connected either directly or by way of an oxygen atom or an optionally substituted amino or methylene group to a typically substituted cyclic or acyclic group. At the opposite end of the sulfonylurea bridge, the amino group, which may have a substituent such as methyl (R being CH3) instead of hydrogen, is connected to a heterocyclic group, typically a symmetric pyrimidine or triazine ring, having one or two substituents such as methyl, ethyl, trifluoromethyl, methoxy, ethoxy, methylamino, dimethylamino, ethylamino and the halogens. Sulfonylurea herbicides can be in the form of the free acid or a salt. In the free acid form the sulfonamide nitrogen on the bridge is not deprotonated (i.e., —S(O)2NHC(O)NH(R)—), while in the salt form the sulfonamide nitrogen atom on the bridge is deprotonated (i.e., —S(O)2NC(O)NH(R)—), and a cation is present, typically of an alkali metal or alkaline earth metal, most commonly sodium or potassium. Sulfonylurea compounds include, for example, compound classes such as pyrimidinylsulfonylurea compounds, triazinylsulfonylurea compounds, thiadiazolylurea compounds, and pharmaceuticals such as antidiabetic drugs, as well as salts and other derivatives thereof. Examples of pyrimidinylsulfonylurea compounds include amidosulfuron, azimsulfuron, bensulfuron, bensulfuron-methyl, chlorimuron, chlorimuron-ethyl, cyclosulfamuron, ethoxysulfuron, flazasulfuron, flucetosulfuron, flupyrsulfuron, flupyrsulfuron-methyl, foramsulfuron, halosulfuron, halosulfuron-methyl, imazosulfuron, mesosulfuron, mesosulfuron-methyl, nicosulfuron, orthosulfamuron, oxasulfuron, primisulfuron, primisulfuron-methyl, pyrazosulfuron, pyrazosulfuron-ethyl, rimsulfuron, sulfometuron, sulfometuron-methyl, sulfosulfuron, trifloxysulfuron and salts and derivatives thereof. Examples of triazinylsulfonylurea compounds include chlorsulfuron, cinosulfuron, ethametsulfuron, ethametsulfuron-methyl, iodosulfuron, iodosulfuron-methyl, metsulfuron, metsulfuron-methyl, prosulfuron, thifensulfuron, thifensulfuron-methyl, triasulfuron, tribenuron, tribenuron-methyl, triflusulfuron, triflusulfuron-methyl, tritosulfuron and salts and derivatives thereof. Examples of thiadiazolylurea compounds include buthiuron, ethidimuron, tebuthiuron, thiazafluron, thidiazuron and salts and derivatives thereof. Examples of antidiabetic drugs include acetohexamide, chlorpropamide, tolbutamide, tolazamide, glipizide, gliclazide, glibenclamide (glyburide), gliquidone, glimepiride and salts and derivatives thereof. In some examples the isolated SuR polypeptides specifically bind to more than one sulfonylurea compound. In some examples the sulfonylurea compound is selected from the group consisting of chlorsulfuron, ethametsulfuron-methyl, metsulfuron-methyl, thifensulfuron-methyl, sulfometuron-methyl, tribenuron-methyl, chlorimuron-ethyl, nicosulfuron, and rimsulfuron.

Compositions also include isolated polynucleotides encoding SuR polypeptides that specifically bind to a tetracycline operator, wherein the specific binding is regulated by a sulfonylurea compound. In some examples the isolated polynucleotides encode sulfonylurea repressor (SuR) polypeptides comprising an amino acid substitution in the ligand binding domain of a wild type tetracycline repressor protein. In class B and D wild type TetR proteins, amino acid residues 6-52 represent the DNA binding domain. The remainder of the protein is involved in ligand binding and subsequent allosteric modification. For class B TetR residues 53-207 represent the ligand binding domain, while residues 53-218 comprise the ligand binding domain for the class D TetR. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid substitution in the ligand binding domain of a wild type TetR(B) protein. In some examples the polynucleotides encode SuR polypeptides comprising an amino acid substitution in the ligand binding domain of a wild type TetR(B) protein of SEQ ID NO: 1.

In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid, or any combination of amino acids, selected from the amino acid diversity shown in FIG. 9, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of a wild type TetR(B) exemplified by SEQ ID NO: 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues shown in FIG. 9, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the isolated polynucleotides encode SuR polypeptides comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues shown in FIG. 9, wherein the amino acid residue position corresponds to the equivalent position using the amino acid numbering of wild type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO: 1.

In some examples the isolated polynucleotides encode SuR polypeptides comprising a ligand binding domain comprising an amino acid substitution at a residue position selected from the group consisting of position 55, 60, 64, 67, 82, 86, 100, 104, 105, 108, 113, 116, 134, 135, 138, 139, 147, 151, 170, 173, 174, 177 and any combination thereof, wherein the amino acid residue position and substitution corresponds to the equivalent position using the amino acid numbering of a wild type TetR(B). In some examples the isolated polynucleotides encode SuR polypeptides further comprising an amino acid substitution at a residue position selected from the group consisting of 109, 112, 117, 131, 137, 140, 164 and any combination thereof. In some examples the wild type TetR(B) polypeptide sequence is SEQ ID NO: 1.

In some examples the isolated polynucleotides encode SuR polypeptides having a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the group consisting of:

-   (a) M or L at amino acid residue position 55; -   (b) A, L or M at amino acid residue position 60; -   (c) A, N, Q, L or H at amino acid residue position 64; -   (d) M, I, L, V, F or Y at amino acid residue position 67; -   (e) N, S or T at amino acid residue position 82; -   (f) F, M, W or Y at amino acid residue position 86; -   (g) C, V, L, M, F, W or Y at amino acid residue position 100; -   (h) R, A or G at amino acid residue position 104 -   (i) A, I, V, F or W at amino acid residue position 105; -   (j) Q or K at amino acid residue position 108; -   (k) A, M, H, K, T, P or V at amino acid residue position 113; -   (l) I, L, M, V, R, S, N, P or Q at amino acid residue position 116; -   (m) I, L, V, M, R, S or W at amino acid residue position 134; -   (n) R, S, N, Q, K or A at amino acid residue position 135; -   (o) A, C, G, H, I, V, R or Tat amino acid residue position 138; -   (p) A, G, I, V, M, W, N, R or Tat amino acid residue position 139; -   (q) I, L, V, F, W, T, S or R at amino acid residue position 147; -   (r) M, L, W, Y, K, R or S at amino acid residue position 151; -   (s) I, L, V or A at amino acid residue position 170; -   (t) A, G or V at amino acid residue position 173; -   (u) L, V, W, Y, H, R, K or S at amino acid residue position 174;     and, -   (v) A, G, I, L, Y, K, Q or Sat amino acid residue position 177,     wherein the amino acid residue position corresponds to the     equivalent position using the amino acid numbering of wild type     TetR(B). In some examples the isolated SuR polynucleotides encode     SuR polypeptides comprising at least 10%, 20%, 30%, 40%, 50%, 55%,     60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%,     77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%,     90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the     amino acid residues are selected from the amino acid residues listed     in (a)-(v) above, wherein the amino acid residue position     corresponds to the equivalent position using the amino acid     numbering of wild type TetR(B). In some examples the wild type     TetR(B) is SEQ ID NO: 1.

In some examples the isolated polynucleotides encode SuR polypeptides selected for enhanced activity on chlorsulfuron having a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the group consisting of:

-   (a) M at amino acid residue position 60; -   (b) A or Q at amino acid residue position 64; -   (c) M, F, Y, I, V or L at amino acid residue position 67; -   (d) N or T at amino acid residue position 82; -   (e) M at amino acid residue position 86; -   (f) C or W at amino acid residue position 100; -   (g) W at amino acid residue position 105; -   (h) Q or K at amino acid residue position 108; -   (i) M, Q, L or H at amino acid residue position 109; -   (j) G, A, S or T at amino acid residue position 112; -   (k) A at amino acid residue position 113; -   (l) M or Q at amino acid residue position 116; -   (m) M or V at amino acid residue position 134; -   (n) G or R at amino acid residue position 138; -   (o) N or V at amino acid residue position 139; -   (p) F at amino acid residue position 147; -   (q) S or L at amino acid residue position 151; -   (r) A at amino acid residue position 164; -   (s) A, L or V at amino acid residue position 170; -   (t) A, G or V at amino acid residue position 173; -   (u) L or W at amino acid residue position 174; and; -   (v) K at amino acid residue position 177,     wherein the amino acid residue position corresponds to the     equivalent position using the amino acid numbering of wild type     TetR(B). In some examples the isolated SuR polynucleotides encode     SuR polypeptides comprising at least 10%, 20%, 30%, 40%, 50%, 55%,     60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%,     77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%,     90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the     amino acid residues are selected from the amino acid residues listed     in (a)-(v) above wherein the amino acid residue position corresponds     to the equivalent position using the amino acid numbering of wild     type TetR(B). In some examples the wild type TetR(B) is SEQ ID NO:     1.

In some examples the isolated polynucleotides encode SuR polypeptides selected for enhanced activity on ethametsulfuron having a ligand binding domain comprising at least 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the amino acid residues are selected from the group consisting of:

-   (a) M or L at amino acid residue position 55; -   (b) A at amino acid residue position 64; -   (c) M, Y, F, I, L or V at amino acid residue position 67; -   (d) M at amino acid residue position 86; -   (e) Cat amino acid residue position 100; -   (f) G at amino acid residue position 104; -   (g) F at amino acid residue position 105; -   (h) Q or K at amino acid residue position 108; -   (i) Q, M, L or H at amino acid residue position 109; -   (j) S, T, G or A at amino acid residue position 112; -   (k) A at amino acid residue position 113; -   (l) S at amino acid residue position 116; -   (m) M or L at amino acid residue position 117; -   (n) M or L at amino acid residue position 131; -   (o) M at amino acid residue position 134; -   (p) Q at amino acid residue position 135; -   (q) A or V at amino acid residue position 137; -   (r) C or G amino acid residue 138; -   (s) I at amino acid residue position 139; -   (t) F or Y at amino acid residue position 140; -   (u) L at amino acid residue position 147; -   (v) L at amino acid residue position 151; -   (w) A at amino acid residue position 164; -   (x) V, A or L at amino acid residue position 170; -   (y) G, A or V at amino acid residue position 173; -   (z) L at amino acid residue position 174; and, -   (aa) N or K at amino acid residue position 177,     wherein the amino acid residue position corresponds to the     equivalent position using the amino acid numbering of wild type     TetR(B). In some examples the isolated SuR polynucleotides encode     SuR polypeptides comprising at least 10%, 20%, 30%, 40%, 50%, 55%,     60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%,     77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%,     90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% of the     amino acid residues are selected from the amino acid residues listed     in (a)-(aa) above, wherein the amino acid residue position     corresponds to the equivalent position using the amino acid     numbering of wild type TetR(B). In some examples the wild type     TetR(B) is SEQ ID NO: 1.

In some examples the isolated polynucleotides encode SuR polypeptides having at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to the ligand binding domain shown as amino acid residues 53-207 of SEQ ID NO: 1, wherein the sequence identity is determined over the full length of the ligand binding domain using a global alignment method. In some examples the global alignment method is GAP, wherein the default parameters are for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

In some examples the isolated polynucleotides encode SuR polypeptides having at least about 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to SEQ ID NO: 1, wherein the sequence identity is determined over the full length of the polypeptide using a global alignment method. In some examples the global alignment method is GAP, wherein the default parameters are for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix.

In some examples the isolated polynucleotides include nucleic acid sequences that selectively hybridize under stringent hybridization conditions to a polynucleotide encoding a SuR polypeptide. Polynucleotides that selectively hybridize are polynucleotides which bind to a target sequence at a level of at least 2-fold over background as compared to hybridization to a non-target sequence. Stringent conditions are sequence-dependent and condition-dependent. Typical stringent conditions are those in which the salt concentration about 0.01 to 1.0 M at pH 7.0-8.3 at 30° C. for short probes (e.g., 10 to 50 nucleotides) or about 60° C. for long probes (e.g., greater than 50 nucleotides). Stringent conditions may include formamide or other destabilizing agents. Exemplary moderate stringency conditions include hybridization in 40 to 45% formamide, 1 M NaCl, 1% SDS at 37° C., and a wash in 0.5× to 1×SSC at 55 to 60° C. Exemplary high stringency conditions include hybridization in 50% formamide, 1 M NaCl, 1% SDS at 37° C., and a wash in 0.1×SSC at 60 to 65° C.

Specificity is impacted by post-hybridization wash conditions, typically via ionic strength and temperature. For DNA-DNA hybrids, the T_(m) can be approximated from the equation of Meinkoth and Wahl, (1984) Anal. Biochem. 138:267-284: T_(m)=81.5° C.+16.6 (log M)+0.41 (% GC)−0.61 (% form)−500/L; where M is the molarity of monovalent cations, % GC is the percentage of guanosine and cytosine nucleotides in the DNA, % form is the percentage of formamide in the hybridization solution, and L is the length of the hybrid in base pairs. An extensive guide to the hybridization of nucleic acids is found in Tijssen, Laboratory Techniques in Biochemistry and Molecular Biology—Hybridization with Nucleic Acid Probes, Part I, Chapter 2 “Overview of principles of hybridization and the strategy of nucleic acid probe assays”, Elsevier, N.Y. (1993); and Current Protocols in Molecular Biology, Chapter 2, Ausubel, et al., Eds., Greene Publishing and Wiley-Interscience, New York (1995). In some examples, the isolated polynucleotides encoding SuR polypeptides specifically hybridize to a polynucleotide of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247 under moderately stringent conditions or under highly stringent conditions.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO: 220) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO: 220) to generate a BLAST bit score of at least 374, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a percent sequence identity of at least 88% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 600, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-1A04 (SEQ ID NO:220) to generate a BLAST e-value score of at least e-60, e-70, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST bit score of at least 387, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a percent sequence identity of at least 92% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 600, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-22 (SEQ ID NO: 7) to generate a BLAST e-value score of at least e-60, e-70, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST bit score of at least 393, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST similarity score of at least 1006, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-29 (SEQ ID NO: 10) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-02 (SEQ ID NO: 3) to generate a BLAST e-value score of at least e-112, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST bit score of at least 388, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST similarity score of at least 996 wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-07 (SEQ ID NO: 4) to generate a BLAST e-value score of at least e-111, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-20 (SEQ ID NO: 6) to generate a BLAST e-value score of at least e-111, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93 %, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a percent sequence identity of at least 93% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L1-44 (SEQ ID NO: 13) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST bit score of at least 381, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST similarity score of at least 978, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3A09 (SEQ ID NO: 1228) to generate a BLAST e-value score of at least e-108, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a percent sequence identity of at least 90% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L6-3H02 (SEQ ID NO: 94) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST bit score of at least 368, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST similarity score of at least 945, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L7-4E03 (SEQ ID NO: 1229) to generate a BLAST e-value score of at least e-105, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a percent sequence identity of at least 86% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L10-84(B12) (SEQ ID NO: 1230) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST bit score of at least 200, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, or 750, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode an SuR polypeptide comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST bit score of at least 320, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a percent sequence identity of at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a percent sequence identity of at least 86% sequence identity, wherein the sequence identity is determined by BLAST alignment using the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the percent sequence identity is determined using a global alignment method using the GAP algorithm with default parameters for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST similarity score of at least 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 750, 800, 850, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST similarity score of at least 819, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST e-value score of at least e-60, e-70, e-75, e-80, e-85, e-90, e-95, e-100, e-105, e-106, e-107, e-108, e-109, e-110, e-111, e-112, e-113, e-114, e-115, e-116, e-117, e-118, e-119, e-120, or e-125, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence that can be optimally aligned with a polypeptide sequence of L13-46 (SEQ ID NO: 1231) to generate a BLAST e-value score of at least e-90, wherein the BLAST alignment used the BLOSUM62 matrix, a gap existence penalty of 11, and a gap extension penalty of 1. In some examples isolated polynucleotide encodes a polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated polynucleotides encode an SuR polypeptide comprising a ligand binding domain from a polypeptide selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the isolated polynucleotides encode SuR polypeptides comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the encoded SuR polypeptide is selected from the group consisting of SEQ ID NO: 3-401, 1206-1213, 1228-1233, or 1240-1243, and the sulfonylurea compound is selected from the group consisting of chlorsulfuron, ethametsulfuron-methyl, metsulfuron-methyl, sulfometuron-methyl, and thifensulfuron-methyl. In some examples the isolated polynucleotides comprise a polynucleotide sequence of SEQ ID NO: 434-832, 1214-1221, 1234-1239, or 1244-1247, or the complementary polynucleotide thereof.

In some examples the isolated SuR polynucleotide encodes an SuR polypeptide having an equilibrium binding constant for a sulfonylurea compound greater than 0.1 nM and less than 10 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound of at least 0.1 nM, 0.5nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM but less than 10 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound of at least 0.1 nM, 0.5nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM but less than 1 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for a sulfonylurea compound greater than 0 nM, but less than 0.1 nM, 0.5nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM, or 10 μM. In some examples the sulfonylurea compound is a chlorsulfuron, an ethametsulfuron, a metsulfuron, a sulfometuron, and/or a thifensulfuron compound.

In some examples the isolated SuR polynucleotide encodes an SuR polypeptide having an equilibrium binding constant for an operator sequence greater than 0.1 nM and less than 10 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for an operator sequence of at least 0.1 nM, 0.5 nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM but less than 10 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for an operator sequence of at least 0.1 nM, 0.5nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM but less than 1 μM. In some examples the encoded SuR polypeptide has an equilibrium binding constant for an operator sequence greater than 0 nM, but less than 0.1 nM, 0.5nM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 5 μM, 7 μM or 10 μM. In some examples the operator sequence is a Tet operator sequence. In some examples the Tet operator sequence is a TetR(A) operator sequence, a TetR(B) operator sequence, a TetR(D) operator sequence, TetR(E) operator sequence, a TetR(H) operator sequence or a functional derivative thereof.

In some examples the isolated polynucleotides encoding SuR polypeptides comprise codon composition profiles representative of codon preferences for particular host cells, or host cell organelles. In some examples the isolated polynucleotides comprise prokaryote preferred codons. In some examples the isolated polynucleotides comprise bacteria preferred codons. In some examples the bacteria is E. coli or Agrobacterium. In some examples the isolated polynucleotides comprise plastid preferred codons. In some examples the isolated polynucleotides comprise eukaryote preferred codons. In some examples the isolated polynucleotides comprise nuclear preferred codons. In some examples the isolated polynucleotides comprise plant preferred codons. In some examples the isolated polynucleotides comprise monocotyledonous plant preferred codons. In some examples the isolated polynucleotides comprise corn, rice, sorghum, barley, wheat, rye, switch grass, turf grass and/or oat preferred codons. In some examples the isolated polynucleotides comprise dicotyledonous plant preferred codons. In some examples the isolated polynucleotides comprise soybean, sunflower, safflower, Brassica, alfalfa, Arabidopsis, tobacco and/or cotton preferred codons. In some examples the isolated polynucleotides comprise yeast preferred codons. In some examples the isolated polynucleotides comprise mammalian preferred codons. In some examples the isolated polynucleotides comprise insect preferred codons.

Compositions also include isolated polynucleotides fully complementary to a polynucleotide encoding an SuR polypeptide, expression cassettes, replicons, vectors, T-DNAs, DNA libraries, host cells, tissues and/or organisms comprising the polynucleotides encoding the SuR polypeptides and/or complements or derivatives thereof. In some examples a DNA library comprising a population of polynucleotides which encode a population of SuR polypeptide variants is provided. In some examples the polynucleotide is stably incorporated into a genome of the host cell, tissue and/or organism. In some examples the host cell is a prokaryote, including E. coli and Agrobacterium strains. In some examples the host is a eukaryote, including for example yeast, insects, plants and mammals.

Methods using the compositions are further provided. In one example methods of regulating transcription of a polynucleotide of interest in a host cell are provided, the methods comprising: providing a cell comprising the polynucleotide of interest operably linked to a promoter comprising at least one tetracycline operator sequence; providing an SuR polypeptide and, providing a sulfonylurea compound, thereby regulating transcription of the polynucleotide of interest. Any host cell can be used, including for example prokaryotic cells such as bacteria, and eukaryotic cells, including yeast, plant, insect, and mammalian cells. In some examples providing the SuR polypeptide comprises contacting the cell with an expression cassette comprising a promoter functional in the cell operably linked to a polynucleotide that encodes the SuR polypeptide.

Methods for generating and selecting diversified libraries to produce additional SuR polynucleotides, including polynucleotides encoding SuR polypeptides with improved and/or enhanced characteristics, e.g., altered binding constants for sulfonylurea compounds and/or the target DNA operator sequence and/or increased stability, all based upon selection of a polynucleotide constituent of the library for the new or improved activities are also provided. In some examples at least one library or population of oligonucleotides designed to introduce sequence modifications and/or diversity to a wild type or modified TetR ligand binding domain polypeptide is provided. In some examples the library or population is designed to introduce modifications and/or diversity to a wild type or modified TetR polypeptide. In some examples, the library or population introduce at least one modification as exemplified in FIG. 9. In some examples the library or population comprises at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or greater distinct oligonucleotides. In some examples the library or population comprises oligonucleotides selected from the oligonucleotides shown in at least one of Table 2, 9, 12, 13, 15, 17, 19 or a combination thereof. In some examples the library or population comprises one or more oligonucleotides selected from the group consisting of SEQ ID NO: 833-882, 885-986, 987-059, 1060-1083, 1084-1124, 1125-1154, 1159-1205.

In some examples the sulfonylurea compound is an ethametsulfuron. In some examples the ethametsulfuron is provided at a concentration of about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100, 200 or 500 μg/ml. In some examples the SuR polypeptide has a ligand binding domain having at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to an SuR polypeptide of SEQ ID NO: 205-401, 1206-1213, or 1228-1233, wherein the sequence identity is determined over the full length of the polypeptide using a global alignment method. In some examples the global alignment method is GAP, wherein the default parameters are for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix. In some examples the polypeptide has a ligand binding domain from a SuR polypeptide selected from the group consisting of SEQ ID NO: 205-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 205-401, 1206-1213, 1228-1233, or 1240-1243. In some examples the polypeptide is encoded by a polynucleotide of SEQ ID NO: 636-832, 1214-1221, 1234-1239, or 1244-1247.

In some examples the sulfonylurea compound is chlorsulfuron. In some examples the chlorsulfuron is provided at a concentration of about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100, 200 or 500 μg/ml. In some examples the SuR polypeptide has a ligand binding domain having at least 50% 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to an SuR polypeptide of SEQ ID NO: 14-204, wherein the sequence identity is determined over the full length of the polypeptide using a global alignment method. In some examples the global alignment method is GAP, wherein the default parameters are for an amino acid sequence % identity and % similarity using GAP Weight of 8 and Length Weight of 2 and the BLOSUM62 scoring matrix. In some examples the polypeptide has a ligand binding domain from a SuR polypeptide selected from the group consisting of SEQ ID NO: 14-204. In some examples the polypeptide is selected from the group consisting of SEQ ID NO: 14-204. In some examples the polypeptide is encoded by a polynucleotide of SEQ ID NO: 445-635.

The ability to capture value in various seed markets will require development of technology for controlling engineered trait distribution. One option is a trait deactivation/activation system using a chemically-regulated gene switch. To date no such system exists, in large part because of the lack of relevant chemistry, for example agricultural-compatible and/or pharmaceutical-based chemistry, that can be used as a ligand for a sensitive gene switch technology.

To develop an agricultural chemical-based ligand gene switch, TetR was modified using protein modeling, DNA shuffling, and a highly sensitive screening mechanism to produce a repressor that specifically recognizes sulfonylurea compounds. For agricultural applications, sulfonylurea compounds are phloem mobile and commercially available, thereby providing a good basis for use as switch ligand chemistry. Following three rounds of modeling and DNA shuffling, repressors that recognize SU chemistry nearly as well as wild type TetR recognizes cognate inducers and yet are totally specific to sulfonylurea chemistry have been generated. These polypeptides comprise true sulfonylurea repressors (SuRs), which have been validated in planta using a newly developed transient assay system to demonstrate functionality of the SuR switch system. While exemplified in an agricultural context, these methods and compositions can be used in a wide variety of other settings and organisms.

In general, a chemical switch system wherein the chemical used penetrates rapidly and is perceived by all cell types in the organism, but does not perturb any endogenous regulatory networks will be most useful. Other important aspects have to do with the behavior of the sensor component, for example the stringency of regulation and response in the absence or presence of inducer. In general a switch system having tight regulation of the “off” state in the absence of inducer and rapid and intense response in the presence of inducer is preferred.

The ability to reversibly turn genes on and off has great utility for the analyses of gene expression and function, particularly for those genes whose products are toxic to the cell. A well characterized control mechanism in prokaryotes involves repressor proteins binding to operator DNA to prevent transcription initiation (Wray and Reznikoff (1983) J Bacteriol 156:1188-1191) and repressor-regulated systems have been developed for controlling expression, both in animals (Wirtz and Clayton (1995) Science 268:1179-1183; Deuschle et al. (1995) Mol Cell Biol 15:1097-1914; Furth et al. (1994) Proc Natl Acad Sci USA 91:9032-9306; Gossen and Bujard (1992) Proc Natl Acad Sci USA 89:5547-5551 and Gossen et al. (1995) Science 268:1766-1769) and plants (Wilde et al. (1992) EMBO J 11:1251-1259; Gatz et al. (1992) Plant J 2:397-404; Roder et al. (1994) Mol Gen Genet 243-32-38 and Ulmasov et al. (1997) Plant Mol Biol 35:417-424).

Two major repressor based systems have been successfully exploited for regulation of plant gene expression: the lac operator-repressor system (Ulmasov et al. (1997) Plant Mol Biol 35:417-424; Wilde et al. (1992) EMBO J 11:1251-1259) and the tet operator-repressor system (Wilde et al. (1992) EMBO J 11:1251-1259; Gatz et al. (1992) Plant J 2:397-404; Roder et al. (1994) Mol Gen Genet 243:32-38; Ulmasov et al. (1997) Plant Mol Biol 35-417-424). Both are repressor/operator based-systems deriving key elements from their corresponding prokaryotic operon, namely the E. coli lactose operon for lac and the transposon Tn10 tetracycline operon for tet. Generally, these systems control the activity of a promoter by placing operator sequences near the transcriptional start site of a gene such that gene expression from the operon is inhibited upon the binding of the repressor protein to its cognate operator sequence. However, in the presence of an inducing agent, the binding of the repressor to its operator is inhibited, thus activating the promoter and enabling gene expression. In the lac system, isopropyl-B-D-thiogalactopyranoside (IPTG) is the commonly used inducing agent, while tetracycline and/or doxycyline are commonly used inducing agents for the tet system.

Expression of the Tn10-operon is regulated by binding of the tet repressor to its operator sequences (Beck et al. (1982) J Bacteriol 150:633-642; Wray and Reznikoff (1983) J Bacteriol 156:1188-1191). The high specificity of tetracycline repressor for the tet operator, the high efficiency of induction by tetracycline and its derivatives, the low toxicity of the inducer, as well as the ability of tetracycline to easily permeate most cells, are the basis for the application of the tet system in somatic gene regulation in eukaryotic cells from animals (Wirtz and Clayton (1995) Science 268:1179-1183; Gossen et al. (1995) Science 268:1766-1769), humans (Deuschle et al. (1995) Mol Cell Biol 15:1907-1914; Furth et al. (1994) Proc Natl Acad Sci USA 91:9302-9306; Gossen and Bujard (1992) Proc Natl Acad Sci USA 89:5547-5551; Gossen et al. (1995) Science 268:1766-1769) and plant cell cultures (Wilde et al. (1992) EMBO J 11:1251-1259; Gatz et al. (1992) Plant J 2:397-404; Roder et al. (1994) Mol Gen Genet 243:32-28; Ulmasov et al. (1997) Plant Mol Biol 35:417-424).

A number of variations of tetracycline operator/repressor systems have been devised. For example, one system based on conversion of the tet repressor to an activator was developed via fusion of the repressor to a transcriptional transactivation domain such as herpes simplex virus VP16 and the tet repressor (tTA, Gossen and Bujard (1992) Proc Natl Acad Sci USA 89:5547-5551). In this system, a minimal promoter is activated in the absence of tetracycline by binding of tTA to tet operator sequences, and tetracycline inactivates the transactivator and inhibits transcription. This system has been used in plants (Weinmann et al. (1994) Plant J 5:559-569), rat hearts (Fishman et al. (1994) J Clin Invest 93:1864-1868) and mice (Furth et al. (1994) Proc Natl Acad Sci USA 91:9302-9306). However, there were indications that the chimeric tTA fusion protein was toxic to cells at levels required for efficient gene regulation (Bohl et al. (1996) Nat Med 3:299-305).

Promoters modified to be regulated by tetracycline and analogs thereof are known (Matzke et al. (2003) Plant Mol Biol Rep 21:9-19; Padidam (2003) Curr Op Plant Biol 6:169-177; Gatz and Quail (1988) Proc Natl Acad Sci USA 85:1394-1397; Ulmasov et al. (1997) Plant Mol Biol 35:417-424; Weinmann, et al. (1994) Plant J 5:559-569). One or more tet operator sequences can be added to a promoter in order to produce a tetracycline inducible promoter. In some examples up to 7 tet operators have been introduced upstream of a minimal promoter sequence and a TetR::VP16 activation domain fusion applied in trans activates expression only in the absence of inducer (Weinmann et al. (1994) Plant J 5:559-569; Love et al. (2000) Plant J 21:579-588). A widely tested tetracycline regulated expression system for plants using the CaMV 35S promoter was developed (Gatz et al. (1992) Plant J 2:397-404) having three tet operators introduced near the TATA box (3XOpT 35S). The 3XOpT 35S promoter generally functioned in tobacco and potato, however toxicity and poor plant phenotype in tomato and Arabidopsis (Gatz (1997) Ann Rev Plant Physiol Plant Mol Biol 48:89-108; Corlett et al. (1996) Plant Cell Environ 19:447-454) were also reported. Another factor is that the tetracycline-related chemistry is rapidly degraded in the light, which tends to confine its use to testing in laboratory conditions.

TetR has been subjected to DNA shuffling to modify its inducer specificity from tetracycline to 4-de(dimethylamino)-6-deoxy-6-demethyl-tetracycline (cmt3) a related but non-inducing compound (Scholz et al. (2003) J Mol Biol 329:217-227) which lacks chemical side groups at positions 4 and 6 and is therefore smaller than tetracycline. The specificity of TetR was altered by narrowing the ligand binding pocket, thereby sterically blocking the natural ligand tetracycline. The starting polypeptide was a TetR(BD) chimera consisting of amino acids 1-50 from TetR(B) and residues 51-208 from TetR(D). Several rounds of evolution and selection were used to shift TetR specificity from tetracycline to cmt3. Non-inducer cmt3 had little starting activity and was brought to the level of tetracycline, yielding an improvement in activity of several thousand-fold, and tetracycline has almost no inducing activity with the mutant repressors. While the ability to shift the specificity of TetR to the cmt3 ligand is exciting, it must be kept in mind that cmt3 is highly related to the natural tetracycline ligand. Based on these experiments, it is not obvious that TetR could be used as the basis for developing specificity to a completely different class of chemical ligands.

To produce a new chemical switch system, we re-designed the TetR system to recognize chemistry viable for use in agriculture. The re-design process was initiated by choosing a registered agrichemical compound having excellent plant uptake and distribution properties, as well as having a size and a shape reasonable for modeling into the wild type TetR ligand binding pocket. The compound chosen, thifensulfuron-methyl (Harmony®) is one of a family of commercially used sulfonylurea type herbicides inhibiting the key plant enzyme in branched chain amino acid biosynthesis, acetolactate synthase (ALS). Thifensulfuron (Ts) and related herbicides are structurally disparate to tetracycline, therefore it was unlikely they would have any starting activity with TetR. DNA shuffling is a powerful technology and can improve affinities for substrates or rate of substrate turnover by several thousand-fold, however has not yet been able to create de novo starting activity. To meet this gap in the evolution pathway a computer modeling strategy was sought that would narrow the search for meaningful amino acid diversity for shuffling. Recently developed modeling technology was used to re-train E. coli periplasmic binding proteins that normally bind to sugars to react to and initiate signaling with completely diverse sets of compounds such as serotonin, L-lactate and trinitrotoluene (Looger et al. (2003) Nature 423:185-190). Using protein design coupled with DNA shuffling and a very sensitive screening system, TetR protein variants that respond to thifensulfuron (Ts) and other related SU compounds have been identified. Following several rounds of DNA shuffling, TetR variants were developed having genetic switch capability with SU ligands (SuRs) similar to that of TetR with tetracycline inducers.

Any method of rational protein design can be used alone or in combination. For example, phylogenetic diversity within a family of protein sequences can be used to identify positions in the primary structure having amino acid substitutions, and the types of substitutions that have occurred and their impact on function. Conserved domain families can also be aligned and similarly examined to identify positions in the primary structure having amino acid substitutions and the types of substitutions that have occurred and the impact on function. The secondary structure(s) and functional domains can be evaluated and various models used to predict tolerance or impact of amino acid substitutions on structure and function. Modeling using the tertiary and/or quaternary structure and ligand, substrate and/or cofactor binding provide further insights into the effects of amino acid substitutions and/or alternate ligands, substrates and/or cofactors interactions with the polypeptide.

To examine the phylogenetic diversity of tetracycline repressors, both a broad family of tetracycline repressor proteins as well as closely related tetracycline repressors were used. Thirty-four proteins were identified and aligned to examine the amino acid diversity at various positions in the repressor family (SEQ ID NO: 1 and 402-433). The broad family of tetracycline repressors comprised a TetR(D) mutant whose structure was determined by crystallization PDB_(—)1A6I (Orth et al. (1998) J Mol Biol 279:439-447) and public sequence deposit accessions A26948, AAA98409, AAD12754, AAD25094, AAD25537, AAP93923, AAR96033, AAW66496, AAW83818, AB014708, ABS19067, CAA24908, CAC80726, CAC81917, EAY62734, NP_(—)387455, NP_(—)387462, NP_(—)511232, NP_(—)824556, P51560, YP_(—)001220607, YP_(—)001370475, YP_(—)368094, YP_(—)620166, YP_(—)772551, ZP_(—)00132379, ZP_(—)01558383, and ZP_(—)01567051. Closely related tetracycline repressors included TetR(A) P03038, TetR(B) P04483, TetR(D) P0ACT4, TetR(E) P21337 and TetR(H) P51561. The alignments of these sequences were used to look at overall sequence diversity as well as diversity in the DNA and the ligand binding domains (see, Example 1 H, SEQ ID NO: 1 and 402-433).

The modular architecture of repressor proteins and the commonality of helix-turn-helix DNA binding domains allows for the creation of SuR polypeptides having altered DNA binding specificity. For example, the DNA binding specificity can be altered by fusing a SuR ligand binding domain to an alternate DNA binding domain. For example, the DNA binding domain from TetR class D can be fused to an SuR ligand binding domain to create SuR polypeptides that specifically bind to polynucleotides comprising a class D tetracycline operator. In some examples a DNA binding domain variant or derivative can be used. For example, a DNA binding domain from a TetR variant that specifically recognizes a tetO-4C operator or a tetO-6C operator could be used (Helbl and Hillen (1998) J Mol Biol 276:313-318; Helbl et al. (1998) J Mol Biol 276:319-324. The four helix bundle formed by helices α8 and α10 in both subunits can be substituted to ensure dimerization specificity when targeting two different operator specific repressor variants in the same cell to prevent heterodimerization (e.g., Rossi et al. (1998) Nat Genet 20:389-393; Berens and Hillen (2003) Eur J Biochem 270:3109-3121). In another example, the DNA binding domain from LexA repressor was fused to GAL4 wherein this hybrid protein recognized LexA operators in both E. coli and yeast (Brent and Ptashne (1985) Cell 43:729-736). In another example, all of the presumptive DNA binding or DNA-recognition R-groups of the 434 repressor were replaced by the corresponding positions of the P22 repressor. Operator binding specificity of the hybrid repressor 434R[α3(P22R)] was tested both in vivo and in vitro and each test showed that this targeted modification of 434 shifted the DNA binding specificity from 434 operator to P22 operator (Wharton and Ptashne (1985) Nature 316:601-605). This work was further extended by creating a heterodimer of wild type 434R and 434R[α3(P22R)] which then specifically recognized a chimeric P22/434 operator sequence (Hollis et al. (1988) Proc Natl Acad Sci USA 85:5834-5838). In another example, the N-terminal half of the AraC protein was fused to the LexA repressor DNA binding domain. The resulting AraC:LexA chimera dimerized, bound LexA operator, and repressed expression of a LexA operator:β-galactosidase fusion gene in an arabinose-responsive manner (Bustos and Schleif (1993) Proc Natl Acad Sci USA 90:5638-5642).

The isolated polynucleotides encoding SuR polypeptides can also be used as substrates for diversity-generating procedures, including mutation, recombination, and recursive recombination reactions, to produce additional SuR polynucleotide and/or polypeptide variants with desired properties. Additionally, the SuR polynucleotides can be used for diversity-generating procedures to produce polynucleotide and/or polypeptide variants having an altered characteristic as compared to the starting material, for example binding to a different ligand inducer. The diversity-generating process produces sequence alterations including single nucleotide substitutions, multiple nucleotide substitutions and insertion or deletion of regions of the nucleic acid sequence. The diversity-generating procedures can be used separately and/or in combination to produce one or more SuR variants or set of variant as well variants of encoded proteins. Individually and collectively, these procedures provide robust, widely applicable ways of generating diversified polynucleotides and polypeptides, as well as sets of polynucleotides and polypeptides, including, libraries. These variants and sets of variants are useful for the engineering or rapid evolution of polynucleotides, proteins, pathways, cells and/or organisms with new and/or improved characteristics. The resulting polynucleotide and/or polypeptide variants can be selected or screened for altered characteristics and/or properties, including altered ligand binding, retention of DNA binding, and/or quantification of binding properties.

Any method can be used to provide sequence diversity to a library. Many diversity-generating procedures, including multigene shuffling and methods for generating modified nucleic acid sequences are available, including for example, Soong et al. (2000) Nat Genet 25:436-39; Stemmer et al. (1999) Tumor Targeting 4:1-4; Ness et al. (1999) Nature Biotech 17:893-896; Chang et al. (1999) Nature Biotech 17:793-797; Minshull and Stemmer (1999) Curr Op Chem Biol 3:284-290; Christians et al. (1999) Nature Biotech 17:259-264; Crameri et al. (1998) Nature 391:288-291; Crameri et al. (1997) Nature Biotech 15:436-438; Zhang et al. (1997) Proc Natl Acad Sci USA 94:4504-4509; Patten et al. (1997) Curr Op Biotech 8:724-733; Crameri et al. (1996) Nature Med 2:100-103; Crameri et al. (1996) Nature Biotech 14:315-319; Gates et al. (1996) J Mol Biol 255:373-386; Stemmer (1996) “Sexual PCR and Assembly PCR” in The Encyclopedia of Molecular Biology (VCH Publishers, New York) pp. 447-457; Crameri and Stemmer (1995) BioTechniques 18:194-195; Stemmer et al. (1995) Gene 164:49-53; Stemmer (1995) Science 270:1510; Stemmer (1995) Bio/Technology 13:549-553; Stemmer (1994) Nature 370:389-391 and Stemmer (1994) Proc Natl Acad Sci USA 91:10747-10751. Mutational methods to generate diversity include, for example, site-directed mutagenesis (Ling et al. (1997) Anal Biochem 254:157-178; Dale et al. (1996) Methods Mol Biol 57:369-374; Smith (1985) Ann Rev Genet 19:423-462; Botstein and Shortle (1985) Science 229:1193-1201; Carter (1986) Biochem J 237:1-7 and Kunkel (1987) “The efficiency of oligonucleotide directed mutagenesis” in Nucleic Acids and Molecular Biology (Eckstein and Lilley, eds., Springer Verlag, Berlin). Mutagenesis methods using uracil containing templates included Kunkel (1985) Proc Natl Acad Sci USA 82:488-492; Kunkel et al. (1987) Methods Enzymol 154:367-382; and Bass et al. (1988) Science 242:240-245. Oligonucleotide-directed mutagenesis methods include Zoller and Smith (1983) Methods Enzymol 100:468-500; Zoller and Smith (1982) Nucl Acids Res 10:6487-6500 and Zoller and Smith (1987) Methods Enzymol 154:329-350. Phosphorothioate-modified DNA mutagenesis methods include Taylor et al. (1985) Nucl Acids Res 13:8749-8764; Taylor et al. (1985) Nucl Acids Res 13:8765-8787; Nakamaye and Eckstein (1986) Nucl Acids Res 14:9679-9698; Sayers et al. (1988) Nucl Acids Res 16:791-802 and Sayers et al. (1988) Nucl Acids Res 16:803-814. Mutagenesis methods using gapped duplex DNA include (Kramer et al. (1984) Nucl Acids Res 12:9441-9456; Kramer and Fritz (1987) Methods Enzymol 154:350-367; Kramer et al. (1988) Nucl Acids Res 16:7207; and Fritz et al. (1988) Nucl Acids Res 16:6987-6999. Additional suitable diversity-generating methods include point mismatch repair (Kramer et al. (1984) Cell 38:879-887); mutagenesis using repair-deficient host strains (Carter et al. (1985) Nucl Acids Res 13:4431-4443; and Carter (1987) Methods Enzymol 154:382-403); deletion mutagenesis (Eghtedarzadeh and Henikoff (1986) Nucl Acids Res 14: 5115); restriction-selection and restriction-purification (Wells et al. (1986) Phil Trans R Soc Lond A 317:415-423); mutagenesis by total gene synthesis (Nambiar et al. (1984) Science 223:1299-1301; Sakamar and Khorana (1988) Nucl Acids Res 14:6361-6372; Wells et al. (1985) Gene 34:315-323 and Grundström et al. (1985) Nucl Acids Res. 13:3305-3316); double-strand break repair (Mandecki (1986) Proc Natl Acad Sci USA 83:7177-7181; and Arnold (1993) Curr Op Biotech 4:450-455). Nucleic acids can be recombined in vitro by any technique or combination of techniques including, e.g., DNAse digestion of nucleic acids to be recombined followed by ligation and/or PCR reassembly of the nucleic acids. For example, sexual PCR mutagenesis can be used in which fragmentation of the DNA molecule is followed by recombination in vitro, based on sequence similarity, between DNA molecules with different but related DNA sequences, followed by fixation of the crossover by extension in a polymerase chain reaction. Similarly, nucleic acids can be recursively recombined in vivo, e.g., by allowing recombination to occur between nucleic acids in cells. Such formats optionally provide direct recombination between nucleic acids of interest, or provide recombination between constructs, vectors, viruses, and/or plasmids comprising the nucleic acids of interest. Whole genome recombination methods can also be used wherein whole genomes of cells or other organisms are recombined, optionally including spiking of the genomic recombination mixtures with desired library components. These methods have many applications, including those in which the identity of a target gene is not known. Any of these processes can be used alone or in combination to generate polynucleotides encoding SuR polypeptides. Any of the diversity-generating methods can be used in a reiterative fashion, using one or more cycles of mutation/recombination or other diversity generation methods, optionally followed by one or more selection methods to generate additional recombinant nucleic acids.

For convenience and high throughput it will often be desirable to screen/select for desired modified nucleic acids in a microorganism, such as in a bacteria such as E. coli, or unicellular eukaryote such as yeast including S. cerevisiae, S. pombe, P. pastoris or protists such as Chlamydomonas, or in model cell systems such as SF9, Hela, CHO, BMS, BY2, or other cell culture systems. In some instances, screening in plant cells or plants may be desirable, including plant cell or explant culture systems or model plant systems such as Arabidopsis, or tobacco. In some examples throughput is increased by screening pools of host cells expressing different modified nucleic acids, either alone or as part of a gene fusion construct. Any pools showing significant activity can be deconvoluted to identify single clones expressing the desirable activity.

Recombinant constructs comprising one or more of nucleic acid sequences encoding a SuR polypeptide are provided. The constructs comprise a vector, such as, a plasmid, a cosmid, a phage, a virus, a bacterial artificial chromosome (BAC), a yeast artificial chromosome (YAC), or the like, into which a polynucleotide encoding a SuR polypeptide has been inserted. In some examples, the construct further comprises regulatory sequences, including, for example, a promoter, operably linked to the sequence. Suitable vectors are well known and include chromosomal, non-chromosomal and synthetic DNA sequences, such as derivatives of SV40; bacterial plasmids; replicons; phage DNA; baculovirus; yeast plasmids; vectors derived from combinations of plasmids and phage DNA, viral DNA such as vaccinia, adenovirus, fowl pox virus, pseudorabies, adenovirus, adeno-associated viruses, retroviruses, geminiviruses, TMV, PVX, other plant viruses, Ti plasmids, Ri plasmids and many others.

The vectors may optionally contain one or more selectable marker genes to provide a phenotypic trait for selection of transformed host cells. Usually, the selectable marker gene will encode antibiotic or herbicide resistance. Suitable genes include those coding for resistance to the antibiotic spectinomycin or streptomycin (e.g., the aadA gene), the streptomycin phosphotransferase (SPT) gene for streptomycin resistance, the neomycin phosphotransferase (NPTII or NPTIII) gene kanamycin or geneticin resistance, the hygromycin phosphotransferase (HPT) gene for hygromycin resistance. Additional selectable marker genes include dihydrofolate reductase or neomycin resistance for eukaryotic cell culture and tetracycline or ampicillin resistance. Genes coding for resistance to herbicides include those which act to inhibit the action of glutamine synthase, such as phosphinothricin or basta (e.g., the bar gene), EPSPS, GOX, or GAT which provide resistance to glyphosate, mutant ALS (acetolactate synthase) which provides resistance to sulfonylurea type herbicides or any other known genes.

In bacterial systems a number of expression vectors are available. Such vectors include, but are not limited to, multifunctional E. coli cloning and expression vectors such as BLUESCRIPT (Stratagene); pIN vectors (Van Heeke and Schuster, (1989) J Biol Chem 264:5503-5509); pET vectors (Novagen, Madison Wis.) and the like. Similarly, in S. cerevisiae a number of vectors containing constitutive or inducible promoters such as alpha factor, alcohol oxidase and PGH may be used for production of polypeptides. For reviews, see, Ausubel and Grant et al. (1987) Meth Enzymol 153:516-544. A variety of expression systems can be used in mammalian host cells, including viral-based systems, such as adenovirus and rous sarcoma virus (RSV) systems. Any number of commercially or publicly available expression systems or derivatives thereof can be used.

In plant cells expression can be driven from an expression cassette integrated into a plant chromosome, or an organelle, or cytoplasmically from an episomal or viral nucleic acid. Numerous plant derived regulatory sequences have been described, including sequences which direct expression in a tissue specific manner, e.g., TobRB7, patatin B33, GRP gene promoters, the rbcS-3A promoter and the like. Alternatively, high level expression can be achieved by transiently expressing exogenous sequences of a plant viral vector, e.g., TMV, BMV, geminiviruses including WDV and the like.

Typical vectors useful for expression of nucleic acids in higher plants are known including vectors derived from the tumor-inducing (Ti) plasmid of Agrobacterium tumefaciens described by Rogers et al. (1987) Meth Enzymol 153:253-277. Exemplary A. tumefaciens vectors include plasmids pKYLX6 and pKYLX7 of Schardl et al. (1987) Gene 61:1-11 and Berger et al. (1989) Proc Natl Acad Sci USA 86:8402-8406 and plasmid pB101.2 that is available from Clontech Laboratories, Inc. (Palo Alto, Calif.). A variety of known plant viruses can be employed as vectors including cauliflower mosaic virus (CaMV), geminiviruses, brome mosaic virus and tobacco mosaic virus.

The SuR may be used to control expression of a polynucleotide of interest. The polynucleotide of interest may be any sequence of interest, including but not limited to sequences encoding a polypeptide, encoding an mRNA, encoding an RNAi precursor, encoding an active RNAi agent, a miRNA, an antisense polynucleotide, a ribozyme, a fusion protein, a replicating vector, a screenable marker, and the like. Expression of the polynucleotide of interest may be used to induce expression of an encoding RNA and/or polypeptide, or conversely to suppress expression of an encoded RNA, RNA target sequence, and/or polypeptide. In specific examples, the polynucleotide sequence may a polynucleotide encoding a plant hormone, plant defense protein, a nutrient transport protein, a biotic association protein, a desirable input trait, a desirable output trait, a stress resistance gene, a herbicide resistance gene, a disease/pathogen resistance gene, a male sterility, a developmental gene, a regulatory gene, a DNA repair gene, a transcriptional regulatory gene or any other polynucleotide and/or polypeptide of interest.

A number of promoters can be used in the compositions and methods. For example, a polynucleotide encoding a SuR polypeptide can be operably linked to a constitutive, tissue-preferred, inducible, developmentally, temporally and/or spatially regulated or other promoters including those from plant viruses or other pathogens which function in a plant cell. A variety of promoters useful in plants is reviewed in Potenza et al. (2004) In Vitro Cell Dev Biol Plant 40:1-22.

Any polynucleotide, including polynucleotides of interest, polynucleotides encoding SuRs, regulatory regions, introns, promoters, and promoters comprising TetOp sequences may be obtained and their nucleotide sequence determined, by any standard method. The polynucleotides may be chemically synthesized in their full-length or assembled from chemically synthesized oligonucleotides (Kutmeier et al. (1994) BioTechniques 17:242). Assembly from oligonucleotides typically involves synthesis of overlapping oligonucleotides, annealing and ligating of those oligonucleotides and PCR amplification of the ligated product. Alternatively, a polynucleotide may be isolated or generated from a suitable source including suitable source a cDNA library generated from tissue or cells, a genomic library, or directly isolated from a host by PCR amplification using specific primers to the 3′ and 5′ ends of the sequence or by cloning using an nucleotide probe specific for the polynucleotide of interest. Amplified nucleic acid molecules generated by PCR may then be cloned into replicable cloning vectors using standard methods. The polynucleotide may be further manipulated using any standard methods including recombinant DNA techniques, vector construction, mutagenesis and PCR (see, e.g., Sambrook et al. (1990) Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.; Ausubel et al., Eds. (1998) Current Protocols in Molecular Biology, John Wiley and Sons, NY).

Any method for introducing a sequence into a cell or organism can be used, as long as the polynucleotide or polypeptide gains access to the interior of at least one cell. Methods for introducing sequences into plants are known and include, but are not limited to, stable transformation, transient transformation, virus-mediated methods, and sexual breeding. Stably incorporated indicates that the introduced polynucleotide is integrated into a genome and is capable of being inherited by progeny. Transient transformation indicates that an introduced sequence does not integrate into a genome such that it is heritable by progeny from the host. Any means can be used to bring together a SuR and polynucleotide of interest operably linked to a promoter comprising TetOp including, for example, stable transformation, transient delivery, cell fusion, sexual crossing or any combination thereof.

Transformation protocols as well as protocols for introducing polypeptides or polynucleotide sequences into plants may vary depending on the type of plant or plant cell targeted for transformation. Suitable methods of introducing polypeptides and polynucleotides into plant cells include microinjection (Crossway et al. (1986) Biotechniques 4:320-334 and U.S. Pat. No. 6,300,543), electroporation (Riggs et al. (1986) Proc Natl Acad Sci USA 83:5602-5606, Agrobacterium-mediated transformation (U.S. Pat. Nos. 5,563,055 and 5,981,840), direct gene transfer (Paszkowski et al. (1984) EMBO J 3:2717-2722), ballistic particle acceleration (U.S. Pat. Nos. 4,945,050, 5,879,918, 5,886,244 and 5,932,782; Tomes et al. (1995) in Plant Cell, Tissue and Organ Culture: Fundamental Methods, ed. Gamborg and Phillips (Springer-Verlag, Berlin); McCabe et al. (1988) Biotechnology 6:923-926). Also see, Weissinger et al. (1988) Ann Rev Genet 22:421-477; Sanford et al. (1987) Particulate Science and Technology 5:27-37; Christou et al. (1988) Plant Physiol 87:671-674; Finer and McMullen (1991) In Vitro Cell Dev Biol 27P:175-182 (soybean); Singh et al. (1998) Theor Appl Genet 96:319-324; Datta et al. (1990) Biotechnology 8:736-740; Klein et al. (1988) Proc Natl Acad Sci USA 85:4305-4309; Klein et al. (1988) Biotechnology 6:559-563; U.S. Pat. Nos. 5,240,855, 5,322,783 and 5,324,646; Klein et al. (1988) Plant Physiol 91:440-444; Fromm et al. (1990) Biotechnology 8:833-839; Hooykaas-Van Slogteren et al. (1984) Nature 311:763-764; U.S. Pat. No. 5,736,369; Bytebier et al. (1987) Proc Natl Acad Sci USA 84:5345-5349; De Wet et al. (1985) in The Experimental Manipulation of Ovule Tissues, ed. Chapman et al. (Longman, N.Y.), pp. 197-209; Kaeppler et al. (1990) Plant Cell Rep 9:415-418; Kaeppler et al. (1992) Theor Appl Genet 84:560-566; D'Halluin et al. (1992) Plant Cell 4:1495-1505; Li et al. (1993) Plant Cell Rep 12:250-255; Christou and Ford (1995) Ann Bot 75:407-413 and Osjoda et al. (1996) Nat Biotechnol 14:745-750. Alternatively, polynucleotides may be introduced into plants by contacting plants with a virus, or viral nucleic acids. Methods for introducing polynucleotides into plants via viral DNA or RNA molecules are known, see, e.g., U.S. Pat. Nos. 5,889,191, 5,889,190, 5,866,785, 5,589,367, 5,316,931 and Porta et al. (1996) Mol Biotech 5:209-221.

The term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which a plant can be regenerated, plant calli, plant clumps and plant cells that are intact in plants or parts of plants such as embryos, pollen, ovules, seeds, leaves, flowers, branches, fruit, kernels, ears, cobs, husks, stalks, roots, root tips, anthers and the like. Progeny, variants and mutants of the regenerated plants are also included.

In some examples, a SuR may be introduced into a plastid, either by transformation of the plastid or by directing a SuR transcript or polypeptide into the plastid. Any method of transformation, nuclear or plastid, can be used, depending on the desired product and/or use. Plastid transformation provides advantages including high transgene expression, control of transgene expression, ability to express polycistronic messages, site-specific integration via homologous recombination, absence of transgene silencing and position effects, control of transgene transmission via uniparental plastid gene inheritance and sequestration of expressed polypeptides in the organelle which can obviate possible adverse impacts on cytoplasmic components (e.g., see, reviews including Heifetz (2000) Biochimie 82:655-666; Daniell et al. (2002) Trends Plant Sci 7:84-91; Maliga (2002) Curr Op Plant Biol 5:164-172; Maliga (2004) Ann Rev Plant Biol 55-289-313; Daniell et al. (2005) Trends Biotechnol 23:238-245 and Verma and Daniell (2007) Plant Physiol 145:1129-1143).

Methods and compositions of plastid transformation are well known, for example, transformation methods include (Boynton et al. (1988) Science 240:1534-1538; Svab et al. (1990) Proc Natl Acad Sci USA 87:8526-8530; Svab et al. (1990) Plant Mol Biol 14:197-205; Svab et al. (1993) Proc Natl Acad Sci USA 90:913-917; Golds et al. (1993) Bio/Technology 11:95-97; O'Neill et al. (1993) Plant J 3:729-738; Koop et al. (1996) Planta 199:193-201; Kofer et al. (1998) In Vitro Plant 34:303-309; Knoblauch et al. (1999) Nat Biotechnol 17:906-909); as well as plastid transformation vectors, elements, and selection (Newman et al. (1990) Genetics 126:875-888; Goldschmidt-Clermont, (1991) Nucl Acids Res 19:4083-4089; Carrer et al. (1993) Mol Gen Genet 241:49-56; Svab et al. (1993) Proc Natl Acad Sci USA 90:913-917; Verma and Daniell (2007) Plant Physiol 145:1129-1143).

Methods and compositions for controlling gene expression in plastids are well known including (McBride et al. (1994) Proc Natl Acad Sci USA 91:7301-7305; Lössl et al. (2005) Plant Cell Physiol 46:1462-1471; Heifetz (2000) Biochemie 82:655-666; Surzycki et al. (2007) Proc Natl Acad Sci USA 104:17548-17553; U.S. Pat. Nos. 5,576,198 and 5,925,806; WO 2005/0544478), as well as methods and compositions to import polynucleotides and/or polypeptides into a plastid, including translational fusion to a transit peptide (e.g., Comai et al. (1988) J Biol Chem 263:15104-15109).

The SuR polynucleotides and polypeptides provide a means for regulating plastid gene expression via a chemical inducer that readily enters the cell. For example, using the T7 expression system for chloroplasts (McBride et al. (1994) Proc Natl Acad Sci USA 91:7301-7305) the SuR could be used to control nuclear T7 polymerase expression. Alternatively, an SuR-regulated promoter could be integrated into the plastid genome and operably linked to the polynucleotide(s) of interest and the SuR expressed and imported from the nuclear genome, or integrated into the plastid. In all cases, application of a sulfonylurea compound is used to efficiently regulate the polynucleotide(s) of interest.

Any type of cell and/or organism, prokaryotic or eukaryotic, can be used with the SuR methods and compositions. For example, any bacterial cell system can be transformed with the compositions. For example, methods of E. coli, Agrobacterium and other bacterial cell transformation, plasmid preparation and the use of phages are detailed, for example, in Current Protocols in Molecular Biology (Ausubel, et al., (eds.) (1994) a joint venture between Greene Publishing Associates, Inc. and John Wiley & Sons, Inc.).

The SuR systems can be used with any eukaryotic cell line, including yeasts, protists, algae, insect cells, avian or mammalian cells. For example, many commercially and/or publicly available strains of S. cerevisiae are available, as are the plasmids used to transform these cells. For example, strains are available from the American Type Culture Collection (ATCC, Manassas, Va.) and include the Yeast Genetic Stock Center inventory, which moved to the ATCC in 1998. Other yeast lines, such as S. pombe and P. pastoris, and the like are also available. For example, methods of yeast transformation, plasmid preparation, and the like are detailed, for example, in Current Protocols in Molecular Biology (Ausubel et al. (eds.) (1994) a joint venture between Greene Publishing Associates, Inc. and John Wiley & Sons, Inc., see Unit 13 in particular). Transformation methods for yeast include spheroplast transformation, electroporation, and lithium acetate methods. A versatile, high efficiency transformation method for yeast is described by Gietz and Woods ((2002) Methods Enzymol 350:87-96) using lithium acetate, PEG 3500 and carrier DNA.

The SuRs can be used in mammalian cells, such as CHO, HeLa, BALB/c, fibroblasts, mouse embryonic stem cells and the like. Many commercially available competent cell lines and plasmids are well known and readily available, for example from the ATCC (Manassas, Va.). Isolated polynucleotides for transformation and transformation of mammalian cells can be done by any method known in the art. For example, methods of mammalian and other eukaryotic cell transformation, plasmid preparation, and the use of viruses are detailed, for example, in Current Protocols in Molecular Biology (Ausubel et al. (eds.) (1994) a joint venture between Greene Publishing Associates, Inc. and John Wiley & Sons, Inc., see, Unit 9 in particular). For example, many methods are available, such as calcium phosphate transfection, electroporation, DEAE-dextran transfection, liposome-mediated transfection, microinjection as well as viral techniques.

Any plant species can be used with the SuR methods and compositions, including, but not limited to, monocots and dicots. Examples of plants include, but are not limited to, corn (Zea mays), Brassica spp. (e.g., B. napus, B. rapa, B. juncea), castor, palm, alfalfa (Medicago sativa), rice (Oryza sativa), rye (Secale cereale), sorghum (Sorghum bicolor, Sorghum vulgare), millet (e.g., pearl millet (Pennisetum glaucum), proso millet (Panicum miliaceum), foxtail millet (Setaria italica), finger millet (Eleusine coracana)), sunflower (Helianthus annuus), safflower (Carthamus tinctorius), wheat (Triticum aestivum), soybean (Glycine max), tobacco (Nicotiana tabacum), potato (Solanum tuberosum), peanuts (Arachis hypogaea), cotton (Gossypium barbadense, Gossypium hirsutum), sweet potato (Ipomoea batatus), cassava (Manihot esculenta), coffee (Coffea spp.), coconut (Cocos nucifera), pineapple (Ananas comosus), citrus trees (Citrus spp.), cocoa (Theobroma cacao), tea (Camellia sinensis), banana (Musa spp.), avocado (Persea americana), fig (Ficus casica), guava (Psidium guajava), mango (Mangifera indica), olive (Olea europaea), papaya (Carica papaya), cashew (Anacardium occidentale), macadamia (Macadamia integrifolia), almond (Prunus amygdalus), sugar beets (Beta vulgaris), sugarcane (Saccharum spp.), Arabidopsis thaliana, oats (Avena spp.), barley (Hordeum spp.), leguminous plants such as guar beans, locust bean, fenugreek, garden beans, cowpea, mungbean, fava bean, lentils, and chickpea, vegetables, ornamentals, grasses and conifers. Vegetables include tomatoes (Lycopersicon esculentum), lettuce (e.g., Lactuca sativa), green beans (Phaseolus vulgaris), lima beans (Phaseolus limensis), peas (Pisium spp., Lathyrus spp.), and Cucumis species such as cucumber (C. sativus), cantaloupe (C. cantalupensis), and musk melon (C. melo). Ornamentals include azalea (Rhododendron spp.), hydrangea (Macrophylla hydrangea), hibiscus (Hibiscus rosasanensis), roses (Rosa spp.), tulips (Tulipa spp.), daffodils (Narcissus spp.), petunias (Petunia hybrida), carnation (Dianthus caryophyllus), poinsettia (Euphorbia pulcherrima), and chrysanthemum. Conifers include pines, for example, loblolly pine (Pinus taeda), slash pine (Pinus elliotii), ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), and Monterey pine (Pinus radiata), Douglas fir (Pseudotsuga menziesii); Western hemlock (Tsuga canadensis), Sitka spruce (Picea glauca), redwood (Sequoia sempervirens), true firs such as silver fir (Abies amabilis) and balsam fir (Abies balsamea) and cedars such as Western red cedar (Thuja plicata) and Alaska yellow cedar (Chamaecyparis nootkatensis).

The plant cells and/or tissue that have been transformed may be grown into plants using conventional methods (see, e.g., McCormick et al. (1986) Plant Cell Rep 5:81-84). These plants may then be grown and self-pollinated, backcrossed, and/or outcrossed, and the resulting progeny having the desired characteristic identified. Two or more generations may be grown to ensure that the characteristic is stably maintained and inherited and then seeds harvested. In this manner transformed/transgenic seed having a DNA construct comprising a polynucleotide of interest and/or modified polynucleotide encoding an SuR stably incorporated into their genome are provided. A plant and/or a seed having stably incorporated the DNA construct can be further characterized for expression, agronomics and copy number.

Sequence identity may be used to compare the primary structure of two polynucleotides or polypeptide sequences, describe the primary structure of a first sequence relative to a second sequence, and/or describe sequence relationships such as variants and homologues. Sequence identity measures the residues in the two sequences that are the same when aligned for maximum correspondence. Sequence relationships can be analyzed using computer-implemented algorithms. The sequence relationship between two or more polynucleotides or two or more polypeptides can be determined by computing the best alignment of the sequences and scoring the matches and the gaps in the alignment, which yields the percent sequence identity and the percent sequence similarity. Polynucleotide relationships can also be described based on a comparison of the polypeptides each encodes. Many programs and algorithms for comparison and analysis of sequences are known. Unless otherwise stated, sequence identity/similarity values provided herein refer to the value obtained using GAP Version 10 (GCG, Accelrys, San Diego, Calif.) using the following parameters: % identity and % similarity for a nucleotide sequence using GAP Weight of 50 and Length Weight of 3, and the nwsgapdna.cmp scoring matrix; % identity and % similarity for an amino acid sequence using GAP Weight of 8 and Length Weight of 2, and the BLOSUM62 scoring matrix (Henikoff and Henikoff (1992) Proc Natl Acad Sci USA 89:10915-10919). GAP uses the algorithm of Needleman and Wunsch (1970) J Mol Biol 48:443-453, to find the alignment of two complete sequences that maximizes the number of matches and minimizes the number of gaps.

Alternatively, polynucleotides and/or polypeptides can be evaluated using other sequence tools. For example, polynucleotides and/or polypeptides can be evaluated using a BLAST alignment tool. A local alignment gaps consists simply of a pair of sequence segments, one from each of the sequences being compared. A modification of Smith-Waterman or Sellers algorithms will find all segment pairs whose scores cannot be improved by extension or trimming, called high-scoring segment pairs (HSPs). The results of the BLAST alignments include statistical measures to indicate the likelihood that the BLAST score can be expected from chance alone. The raw score, S, is calculated from the number of gaps and substitutions associated with each aligned sequence wherein higher similarity scores indicate a more significant alignment. Substitution scores are given by a look-up table (see PAM, BLOSUM). Gap scores are typically calculated as the sum of G, the gap opening penalty and L, the gap extension penalty. For a gap of length n, the gap cost would be G+Ln. The choice of gap costs, G and L is empirical, but it is customary to choose a high value for G (10-15) and a low value for L (1-2). The bit score, S′, is derived from the raw alignment score S in which the statistical properties of the scoring system used have been taken into account. Bit scores are normalized with respect to the scoring system, therefore they can be used to compare alignment scores from different searches. The E-Value, or expected value, describes the likelihood that a sequence with a similar score will occur in the database by chance. It is a prediction of the number of different alignments with scores equivalent to or better than S that are expected to occur in a database search by chance. The smaller the E-Value, the more significant the alignment. For example, an alignment having an E value of e⁻¹¹⁷ means that a sequence with a similar score is very unlikely to occur simply by chance. Additionally, the expected score for aligning a random pair of amino acid is required to be negative, otherwise long alignments would tend to have high score independently of whether the segments aligned were related. Additionally, the BLAST algorithm uses an appropriate substitution matrix, nucleotide or amino acid and for gapped alignments uses gap creation and extension penalties. For example, BLAST alignment and comparison of polypeptide sequences are typically done using the BLOSUM62 matrix, a gap existence penalty of 11 and a gap extension penalty of 1. Unless otherwise stated, scores reported from BLAST analyses were done using the BLOSUM62 matrix, a gap existence penalty of 11 and a gap extension penalty of 1.

UniProt protein sequence database is a repository for functional and structural protein data and provides a stable, comprehensive, fully classified, richly and accurately annotated protein sequence knowledgebase, with extensive crossreferences and querying interfaces freely accessible to the scientific community. The UniProt site has a tool, UniRef, that provides a cluster of proteins have 50%, 90% or 100% sequence identity to a protein sequence of interest from the database. For example, using TetR(B) (UniProt reference P04483) gives a cluster of 18 proteins having 90% sequence identity to P04483:

RefID Protein Name Species Length P04483 TetR class B from transposon E. coli 207 Tn10 B1VCF0 TetR protein E. coli 208 A0ZSZ1 Tetracycline resistant gene Photobacterium sp. 208 repressor TC21 A4LA82 Tetracycline repressor protein Edwardsiella tarda 208 A4V9K4 Tetracycline repressor Salmonella enterica 208 A8R6K3 Tetracycline repressor protein Salmonella enterica 208 subsp. enterica serovar Choleraesuis Q573N4 Tetracycline repressor protein uncultured 208 bacterium Q7BQ37 TetR Shigella flexneri 208 Q9S455 TetR Salmonella typhi 208 A4IUI5 Tetracycline repressor protein Yersinia ruckeri 207 R, class B Q1A2K5 Tetracycline resistance E. coli 207 repressor protein Q6MXH5 TetR class B from transposon Serratia marcescens 207 tn10 Q79VX4 TetR protein Salmonella 207 typhimurium Q7AZW7 Tet repressor protein Pasteurella 207 aerogenes Q7AK84 Repressor of tet operon Plasmid R100 207 Q6QR72 Tetracycline repressor protein E. coli 208 Q93F26 Tet repressor Shigella flexneri 2a 208 Q8L0M9 Putative tetracycline repressor Neisseria 205 protein meningitidis

These protein sequences can be used as sources for sequence diversity for protein design and/or directed evolution of the ligand binding domain. Further, these protein sequences can be used as sources for operator binding domains for chimeric repressor proteins, or for design and/or evolution of the operator binding domain.

The properties, domains, motifs and function of tetracycline repressors are well known, as are standard techniques and assays to evaluate any derived repressor comprising one or more amino acid substitutions. The structure of the class D TetR protein comprises 10 alpha helices with connecting loops and turns. The 3 N-terminal helices form the DNA-binding HTH domain, which has an inverse orientation as compared to HTH motifs in other DNA-binding proteins. The core of the protein, formed by helices 5-10, comprises the dimerization interface domain, and for each monomer comprises the binding pocket for ligand/effector and divalent cation cofactor (Kisker et al. (1995) J Mol Biol 247:260-180; Orth et al. (2000) Nat Struct Biol 7:215-219). Any amino acid change may comprise a non-conservative or conservative amino acid substitution. Conservative substitutions generally refer to exchanging one amino acid with another having similar chemical and/or structural properties (see, e.g., Dayhoff et al. (1978) Atlas of Protein Sequence and Structure, Natl Biomed Res Found, Washington, D.C.). Different clustering of amino acids by similarity have been developed depending on the property evaluated, such as acidic vs. basic, polar vs. non-polar, amphipathic and the like and be used when evaluating the possible effect of any substitution or combination of substitutions.

Numerous variants of TetR have been identified and/or derived and extensively studied. In the context of the tetracycline repressor system, the effects of various mutations, modifications and/or combinations thereof have been used to extensively characterize and/or modify the properties of tetracycline repressors, such as cofactor binding, ligand binding constants, kinetics and dissociation constants, operator binding sequence constraints, cooperativity, binding constants, kinetics and dissociation constants and fusion protein activities and properties. Variants include TetR variants with a reverse phenotype of binding the operator sequence in the presence of tetracycline or an analog thereof, variants having altered operator binding properties, variants having altered operator sequence specificity and variants having altered ligand specificity and fusion proteins. See, for example, Isackson and Bertrand (1985) Proc Natl Acad Sci USA 82:6226-6230; Smith and Bertrand (1988) J Mol Biol 203:949-959; Altschmied et al. (1988) EMBO J 7:4011-4017; Wissmann et al. (1991) EMBO J 10:4145-4152; Baumeister et al. (1992) J Mol Biol 226:1257-1270; Baumeister et al. (1992) Proteins 14:168-177; Gossen and Bujard (1992) Proc Natl Acad Sci USA 89:5547-5551; Wasylewski et al. (1996) J Protein Chem 15:45-58; Berens et al. (1997) J Biol Chem 272:6936-6942; Baron et al. (1997) Nucl Acids Res 25:2723-2729; Helbl and Hillen (1998) J Mol Biol 276:313-318; Urlinger et al. (2000) Proc Natl Acad Sci USA 97:7963-7968; Kamionka et al. (2004) Nucl Acids Res 32:842-847; Bertram et al. (2004) J Mol Microbiol Biotechnol 8:104-110; Scholz et al. (2003) J Mol Biol 329: 217-227; and patent publication US 2003/0186281.

The three-dimensional structures of tetracycline repressors, and tetracycline repressor variants, coupled to ligand and/or co-factor(s), and bound to operator sequence are known (see, for example, Kisker et al. (1995) J Mol Biol 247:260-280; Orth et al. (1998) J Mol Biol 279:439-447; Orth et al. (1999) Biochemistry 38:191-198; Orth et al. (2000) Nat Struct Biol 7:215-219; Luckner et al. (2007) J Mol Biol 368:780-790) providing extremely well characterized structure(s), identification of domains and individual amino acids associated with various functions and binding properties, and predictive model(s) for the potential effects of any amino acid substitution(s), as well as the possible structural bases for the phenotype(s) of known tetracycline repressor mutants. One example of percent sequence identity observed within tetracycline repressor family members is shown below.

% polypeptide sequence identity between TetR family members A E B D H TetR Class (P03038) (P21337) (P04483) (P0ACT4) (P51561) A (P03038) 100 44 51 48 50 E (P21337) 100 51 49 50 B (P04483) 100 64 64 D (P0ACT4) 100 58 H (P51561) 100

Examples Example 1 Evolution of TetR for Recognition by sulfonylurea Compounds

A. Computational Modeling

The 3-D crystal structures of the class D tetracycline repressor (isolated from E. coli; TET-bound dimer, 1 DU7 (Orth et al. (2000) Nat Struct Biol 7:215-219); and DNA-bound dimer, 1QPI (Orth et al. (2000) Nat Struct Biol 7:215-219)), were used as the design scaffold for computational replacement of the tetracycline (TET) molecule by the thifensulfuron-methyl (Ts, Harmony®) molecule in the ligand binding pocket. TET and sulfonylureas (SUs) are generally similar in size and have aromatic ring-based structures with hydrogen bond donors and acceptors, potentially allowing SU binding to a mutated TetR. However, there are notable differences between the tetracycline family and SU family of molecules. TET is internally rigid and fairly flat, with one highly-hydrogen-bonding face with hydroxyls and ketones, log P˜−0.3. Sulfonylureas (SUs) are more highly flexible and aromatic, with a core sulfonyl-urea moiety typically connecting a substituted benzene, pyridine, or thiophene (as in the case of Harmony®) on one side with a substituted pyrimidine or 1,3,5-triazine on the other side. Although having different functional groups, the log P of Harmony® is similar (˜0.02 at pH 7) to that of tet. A best-posed Harmony® molecule was positioned by molecular modeling in the TetR binding pocket in silico (FIG. 1). Based on this model, seventeen amino acid residue positions (60, 64, 82, 86, 100, 104, 105, 113, 116, 134, 135, 138 and 139 from monomer A and positions 147, 151, 174 and 177 from monomer B, using TetR(B) numbering) were determined to be in sufficiently close proximity to a docked Harmony® as to be recruited into a binding surface. Computational side-chain optimization was employed to design sets of amino acids at each of the 17 positions deemed to be most compatible with SU binding. This resulted in a library with (4, 5, 4, 4, 5, 3, 8, 11, 10, 10, 8, 8, 7, 9, 6, 7 and 5) amino acids at the 17 positions, for a total designed library size of 4×10¹³. The choice of amino acids at the library positions was dictated by steric and physicochemical considerations to fit ligand docking into the ligand pocket.

The wild type class B TetR from Tn10 was chosen as the starting molecule for generation of shuffling derivatives (SEQ ID NO: 2). It is slightly different than the sequence used in computational design (P0ACT4, class D, for which the high-resolution crystal structure 1DU7 is available), but only subtly affects ligand binding. A comparison of TetR(D) (SEQ ID NO: 401) and TetR(B) (SEQ ID NO: 2) is shown below with positions involved in tet recognition and binding in bold:

  1        .         .         .         .         .         . 1DU7     SRLNRESVIDAALELLNETGIDGLTTRKLAQKLGIEQPTLYWHVKNKRALLDALAVEI Class B   MGSRLDKSKVINSALELLNEVGIEGLTTRKLAQKLGVEQPTLYWHVKNKRALLDALAIEM  61        .         .         .         .         .         . 1DU7   LARHHDYSLPAAGESWQSFLRNNAMSFRRALLRYRDGAKVHLGTRPDEKQYDTVETQLRF Class B   LDRHHTHFCPLEGESWQDFLRNNAKSFRCALLSHRDGAKVHLGTRPTEKQYETLENQLAF 121        .         .         .         .         .         . 1DU7   MTENGFSLRDGLYAISAVSHFTLGAVLEQQEHTAALTDRPAAPDENLPPLLREALQIMDS Class B   LCQQGFSLENALYALSAVGHFTLGCVLEDQEHQVAKEERETPTTDSMPPLLRQAIELFDH 181        .         .        208 1DU7   DDGEQAFLHGLESLIRGFEVQLTALLQIV Class B   QGAEPAFLFGLELIICGLEKQLKCESGS-

The starting polynucleotide used to express TetR was synthesized commercially and restriction sites were added for functionality in library construction and further manipulation (DNA2.0, Menlo Park, Calif., USA). Added restriction sites include an NcoI site at the 5′ end, a SacI site 5′ of the ligand binding domain (LBD) and an AscI site following the stop codon. This allows library construction to be localized in a ˜480 by DNA segment containing the ligand binding region to avoid inadvertent mutations in the other regions, such as the DNA binding domain. The synthetic gene was operably linked downstream of an arabinose inducible promoter, P_(BAD), using Ncoi/AscI to create TetR expression vector pVER7314 (FIG. 2). The addition of the NcoI site at the 5′ end of the coding region resulted in the insertion of a glycine after the N-terminal methionine at amino acid position one (SEQ ID NO: 2). This sequence was used as the wild type TetR control in all assays unless otherwise noted, and observed activity was equivalent to TetR without the serine insertion (SEQ ID NO: 1). However, all references to amino acid positions and changes designed and observed use the amino acid numbering of wild type TetR(B) (207 aa) e.g., SEQ ID NO: 1.

B. Library Design

Due to the large number of designed substitutions at many positions in close proximity with one another the computed library (Table 1, Designed Library) was not easily encodable with a small number of degenerate codons. This is particularly evident in sequence regions such as amino acids 134, 135, 138 and 139, which could reasonably be encoded by a single primer. For this reason, the sequence library fabricated and tested in the lab featured the designed amino acid set at 6/17 positions, slightly enlarged at 1/17 positions, and fully degenerate (NNK codon) at 10/17 positions (Table 1). This resulted in much higher predicted sequence diversity, a total of 3×10¹⁹ sequences.

TABLE 1 WT Designed Actual Residue residue Library Library 60 L A L K M A L K M 64 H A N Q H L A N Q H L 82 N A N S T A N S T 86 F M F W Y M F W Y 100 H H M F W Y All 20 aa's 104 R A R G A R G 105 P A N D G P S T V All 20 aa's 113 L A R N D Q E K M S T V A R N D Q E K M S T V I P L G H 116 Q A R N Q E I K M T V All 20 aa's 134 L A R I L K M F W Y V All 20 aa's 135 S A R N Q H K S T A R N Q H K S T 138 G A H K M F S Y W All 20 aa's 139 H A R Q H L K Y All 20 aa's 147 E A R Q E H L K M Y All 20 aa's 151 H A Q H K I L All 20 aa's 174 I A R Q E L K M All 20 aa's 177 F A R L K M All 20 aa's

The constructed library, termed ‘L1’, was encoded with a total of fifty oligonucleotides (Table 2) rather than the thousands that would have been required to completely specify the designed target library. Table 2 also includes two PCR amplification primers.

TABLE 2 Oligo SEQ ID Oligo Sequence ID L1:01 TATTGGCATGTAAAAAATAAGCGAGCTCTGCTCGACGCCT 833 TA L1:02 GCCATTGAGATGAWGGATAGGCACCWGACTCACTTTGCCCT 834 L1:03 GCCATTGAGATGAWGGATAGGCACMATACTCACTTTGCCCT 835 L1:04 GCCATTGAGATGAWGGATAGGCACGCGACTCACTTTGCCCT 836 L1:05 GCCATTGAGATGACGGATAGGCACCWGACTCACTTTGCCCT 837 L1:06 GCCATTGAGATGACGGATAGGCACMATACTCACTTTGCCCT 838 L1:07 GCCATTGAGATGACGGATAGGCACGCGACTCACTTTGCCCT 839 L1:08 GCCATTGAGATGATGGATAGGCACCWGACTCACTTTGCCCT 840 L1:09 GCCATTGAGATGATGGATAGGCACMATACTCACTTTGCCCT 841 L1:10 GCCATTGAGATGATGGATAGGCACGCGACTCACTTTGCCCT 842 L1:11 TTAGAAGGGGAAAGCTGGCAAGATTTTTTACGTAATAACG 843 CT L1:12 TTAGAAGGGGAAAGCTGGCAAGATTTTTTACGTAATDCTG 844 CT L1:13 AAAAGTTWTAGATGTGCTTTACTAAGTCATCGCGATGGAG 845 CA L1:14 AAAAGTTGGAGATGTGCTTTACTAAGTCATCGCGATGGAG 846 CA L1:15 AAAAGTATGAGATGTGCTTTACTAAGTCATCGCGATGGAG 847 CA L1:16 AAAGTANNKTTAGGTACAGCGNNKACAGAAAAACAGTATG 848 AA L1:17 AAAGTANNKTTAGGTACASGCNNKACAGAAAAACAGTATG 849 AA L1:18 ACTVNSGAAAATNNKTTAGCCTTTTTATGCCAACAAGGTT 850 TT L1:19 TCACTAGAGAATGCATTATATGCANNSRCCGCTGTGNNKN 851 NK L1:20 TCACTAGAGAATGCATTATATGCANNSMGCGCTGTGNNKN 852 NK L1:21 TCACTAGAGAATGCATTATATGCANNSMAKGCTGTGNNKN 853 NK L1:22 TTTACTTTAGGTTGCGTATTGNNKGATCAAGAGNNKCAAG 854 TC L1:23 GCTAAAGAAGAAAGGGAAACACCTACTACTGATAGTATGC 855 CG L1:24 CCATTATTACGACAAGCTNNKGAATTANNKGATCACCAAG 856 GT L1:25 GCAGAGCCAGCCTTCTTATTCGGCCTTGAATTGATCATAT 857 GC L1:26 GGATTAGAAAAACAACTTAAATGTGAAAGTGGGTCTTAAG 858 GC L1:27 CCTATCCWTCATCTCAATGGCTAAGGCGTCGAGCAGAGCT 859 CG L1:28 CCTATCCGCCATCTCAATGGCTAAGGCGTCGAGCAGAGCT 860 CG L1:29 CCTATCCAGCATCTCAATGGCTAAGGCGTCGAGCAGAGCT 861 CG L1:30 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGTCWGG 862 TG L1:31 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGTATKG 863 TG L1:32 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGTCGCG 864 TG L1:33 TAAAGCACATCTAWAACTTTTAGCGTTATTACGTAAAAAA 865 TC L1:34 TAAAGCACATCTCCAACTTTTAGCGTTATTACGTAAAAAA 866 TC L1:35 TAAAGCACATCTCATACTTTTAGCGTTATTACGTAAAAAA 867 TC L1:36 TAAAGCACATCTAWAACTTTTAGCAGHATTACGTAAAAAA 868 TC L1:37 TAAAGCACATCTCCAACTTTTAGCAGHATTACGTAAAAAA 869 TC L1:38 TAAAGCACATCTCATACTTTTAGCAGHATTACGTAAAAAA 870 TC L1:39 CGCTGTACCTAAMNNTACTTTTGCTCCATCGCGATGACTT 871 AG L1:40 GCSTGTACCTAAMNNTACTTTTGCTCCATCGCGATGACTT 872 AG L1:41 GGCTAAMNNATTTTCSNBAGTTTCATACTGTTTTTCTGTM 873 NN L1:42 ATATAATGCATTCTCTAGTGAAAAACCTTGTTGGCATAAA 874 AA L1:43 CAATACGCAACCTAAAGTAAAMNNMNNCACAGCGGYSNNT 875 GC L1:44 CAATACGCAACCTAAAGTAAAMNNMNNCACAGCGCKSNNT 876 GC L1:45 CAATACGCAACCTAAAGTAAAMNNMNNCACAGCMTKSNNT 877 GC L1:46 TGTTTCCCTTTCTTCTTTAGCGACTTGMNNCTCTTGATCM 878 NN L1:47 MNNAGCTTGTCGTAATAATGGCGGCATACTATCAGTAGTA 879 GG L1:48 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCMNNTAAT 880 TC L1:49 TTTAAGTTGTTTTTCTAATCCGCATATGATCAATTCAAGG 881 CC L1:50 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCACA 882 L1:5′ CATGTAAAAAATAAGCGAGCTCTG 883 L1:3′ GGGAACTTCGGCGCGCCTTAAGAC 884

Assembly of the ‘L1’ oligos was carried out by overlap extension (Ness, et al., (2002) Nat Biotech 20:1251-1255) to generate a PCR fragment bordered by SacI/AscI restriction sites. Conditions for assembly of all library fragments were as follows: oligonucleotides representing the library are normalized to a concentration of 10 μM and then equal volumes mixed to create a 10 μM pool. PCR amplification of library fragments was performed in six identical 25 μl reactions containing: 1 M pooled library oligos; 0.5 μM of each rescue primer: L1:5′ and L1:3′ and 200 M dNTP's in a Herculase II directed reaction (Stratagene, La Jolla, Calif., USA). Conditions for PCR were 98° C. for 1 min (initial denature), followed by 25 cycles of 95° C. denature for 20 seconds, annealing for 45 seconds between 45° C. and 55° C. (gradient), then extending the template for 30 seconds at 72° C. A final extension of 72° C. for 5 minutes completes the reaction. Wild type TetR(B) is excised from the P_(BAD)-tetR expression vector pVER7314 by digestion with SacI/AscI. The pVER7314 backbone fragment is treated with calf intestinal phosphatase and purified, then the fully extended library fragment pool (˜500 bp) digested with SacI/AscI restriction enzymes are inserted to generate the L1 plasmid library. Approximately 50 random clones from library L1 were sequenced and the information compiled for quality control purposes. The results indicated that nearly all amino acids targeted in the diversity set were represented (data not shown). Sequencing revealed that 17% of the sequences contained stop codons. This is less than the predicted 27% (e.g., 10 positions having 1/32 codons be a stop codon, 1−(31/32)¹⁰˜27%). Additionally, sequence analysis showed that 13% of the clones had frame shifts due to mistakes in the overlap extension process. Thus, overall approximately 30% of the library consisted of clones encoding truncated polypeptides.

C. Screen Set Up

In order to test the library for rare clones reacting to thifensulfuron-methyl (Ts) a sensitive E. coli based genetic screen was developed. The screen is a modification of an established assay system (Wissmann et al. (1991) Genetics 128:225-232). The screen consists of two parts: a repressor pre-screen followed by an induction screen. For this purpose an E. coli strain was developed having both functionalities. For the repressor prescreen a genetic cascade was developed whereby an nptIII gene encoding kanamycin resistance is under the control of a lac promoter. The lac promoter is repressed by the Lac repressor encoded by lacI, whose expression is in turn controlled by the tet promoter (PtetR). The tet promoter is repressed by TetR which blocks LacI production and thus ultimately enables kanamycin resistance to be expressed.

Since the tet regulon has bivalent promoters, one promoter for tetR and one promoter for tetA, the same strain was engineered with the E. coli lacZ gene encoding enzyme reporter β-galactosidase under control of the tetA promoter (PtetA). The dual regulon encoding both lacI and lacZ was then bordered by strong transcriptional terminators: the E. coli RNA ribosomal operon terminator rrnB T1-T2 (Ghosh et al. (1991) J Mol Biol 222:59-66) and the E. coli RNA polymerase subunit C terminator rpoC, such that spurious transcripts read in the direction of either tet promoter would not interfere with expression of any other transcript. In the presence of functional TetR, the strain exhibits a lac⁻ phenotype and colonies can be easily scored for induction by novel chemistry with X-gal, wherein induction gives increased blue colony color. In addition, induction with novel chemistry in liquid cultures can be measured quantitatively by employing β-galactosidase enzyme assays with either colorimetric or fluorimetric substrates.

A further refinement of the host strain is that the to/C locus was knocked out with the incoming Plac-nptIII reporter. This was done to obtain better penetration of SU compounds into E. coli (Robert LaRossa—DuPont: personal communication). A strong transcriptional terminator, T22 from S. typhimurium phage P22, was placed upstream of the lac promoter to prevent unregulated leaky expression of the conditional kanamycin resistance marker. The name of the final engineered strain is E. coli KM3.

The population of shuffled tetR LBD's was cloned into an Ap^(r)/ColE1 based vector pVER7314 behind the P_(BAD) promoter. This was designed to enable fine control of TetR expression by variation of arabinose concentrations in the growth medium (Guzman et al. (1995) J Bacteriol 177:4121-4130). Despite being under the control of the P_(BAD) promoter, TetR protein is expressed at a sufficient level in the absence of added arabinose to enable selection for kanamycin resistance in strain KM3. Nevertheless, expression can be increased by addition of arabinose, for example, if a change in assay stringency is desired.

D. Library Screening

Following assembly of L1 oligos and capture in vector pVER7314, the resulting library was transformed into E. coli strain KM3 and plated on LB containing 50 μg/ml carbenicillin to select for library plasmids, and 60 μg/ml kanamycin to select for the active repressor population in the absence of target ligand (“apo-repressors”). DNA sequence analysis of this selected population indicated that this step highly enriched several library positions, suggesting that few amino acid combinations in the ligand binding domain lead to a conformation compatible with DNA binding by the N-terminal domain. In addition, this step eliminated clones with premature stop codons and or frame shift mutations. Subsequently, these apo-repressor sequences were screened for alteration in repressor activity in the presence of Harmony® (Ts). This was done by replica plating the Km^(r) pre-selected population from liquid cultures in 384-well format onto M9 agar containing 0.1% glycerol as carbon source, 0.04% casamino acids (to prevent branched chain amino acid starvation caused by sulfonylurea application), 50 μg/ml carbenicillin for plasmid maintenance, 0.004% X-gal to detect galactosidase activity, and +/−SU inducer Ts at 20 μg/ml. Initial hits were identified from a population of nearly 20,000 colonies screened for response to Ts following incubation at 30° C. for 2 days. Fourteen putative ‘hits’ identified were then re-tested under the same conditions but in 96-well format (FIG. 3).

DNA sequence analysis revealed that clones L1-3 and L1-19 are identical and that the most intensely responding hits (L-2, -3(19), -5, -9, -11 and -20) had significant enrichment at several library positions, indicating an involvement in ligand interaction, directly or indirectly. The same library was then re-screened to identify a further 10 hits to bring the total number of clones to 23.

All 23 putative hits were subsequently screened in the same plate assay format with a panel of nine sulfonylurea (SU) compounds registered for commercial use (Table 3), wherein 11 hits were found to respond significantly to other SU ligands (Table 4). For this experiment, E. coli clones encoding L1 hits or wt TetR (SEQ ID NO: 2) were arrayed in 96-well format and stamped onto M9 X-gal assay media with or without test SU compounds at 20 μg/ml. Following 48 hrs growth at 30° C. the plates were digitally imaged and the colony color intensity converted to relative values of β-galactosidase activity. Inducers used: thifensulfuron (Ts), metsulfuron (Ms), sulfometuron (Sm), ethametsulfuron (Es), tribenuron (Tb), chlorimuron (Ci), nicosulfuron (Ns), rimsulfuron (Rs), chlorsulfuron (Cs) at 20 ppm and anhydrotetracycline (atc) as the positive control at 0.4 μM for induction of wt TetR. Surprisingly, some sulfonylurea compounds, particularly chlorimuron, ethametsulfuron, and chlorsulfuron were more potent activators than the starting ligand Harmony®.

TABLE 3 SU Compound Product Common Name Name Commercial Use Thifensulfuron-methyl (Ts) Harmony ® Cereals, corn, soybean Metsulfuron-methyl (Ms) Ally ® Cereals, pasture Sulfometuron-methyl (Sm) Oust ® Vegetation management Ethametsulfuron-methyl Muster ® Canola (Es) Tribenuron-methyl (Tb) Express ® Cereal, sunflower Chlorimuron-ethyl (Ci) Classic ® Soybean Nicosulfuron (Ns) Accent ® Corn Rimsulfuron (Rs) Matrix ® Corn, tomato, potato Chlorsulfuron (Cs) Glean ® Cereals

TABLE 4 Inducer clone None Ts Ms Sm Es Tb Ci Ns Rs Cs atc L1-2 1.0 1.6 1.9 4.7 5.8 1.7 13.6 1.3 1.3 4.1 1.2 L1-7 0.0 0.1 0.2 6.4 0.1 0.2 16.5 0.1 0.2 3.1 0.0 L1-9 0.3 1.1 1.2 0.6 11.8 0.4 9.8 0.3 0.4 23.6 0.3 L1-20 1.4 2.6 12.4 6.0 15.0 2.6 13.5 1.6 2.0 22.0 2.0 L1-22 0.1 0.0 0.1 17.2 0.3 0.3 10.4 0.2 0.1 0.2 0.0 L1-24 0.1 0.3 0.4 3.1 0.2 1.6 22.1 0.3 0.3 3.3 0.1 L1-28 0.0 0.1 18.8 1.1 0.8 0.3 14.6 0.1 0.2 5.8 0.0 L1-29 0.0 0.0 13.5 2.7 1.7 0.3 20.9 0.1 0.1 15.8 0.0 L1-31 0.3 0.9 0.5 0.9 13.7 0.1 1.1 0.5 0.4 1.4 0.4 L1-38 9.5 16.7 14.7 18.3 14.8 15.8 15.3 8.7 9.5 14.0 6.4 L1-44 0.2 1.9 2.9 0.4 2.4 0.4 6.7 0.4 0.3 12.0 0.2 TetR 0.0 0.0 0.0 0.1 0.0 0.1 0.1 0.1 0.1 0.0 25.0

The amino acid substitutions for these eleven top hits are summarized in Table 5. The sequences are compared to wild type TetR(B) and only positions having differences are shown using the numbering according to TetR(B) (e.g., SEQ ID NO: 1). A dash in the alignment indicates no change relative to wt TetR ligand binding domain.

TABLE 5 60 64 82 86 100 104 105 113 116 134 135 138 139 147 151 164 174 177 203 205 TetR (B) L H N F H R P L Q L S G H E H D I F C S L1-02 — A — — C A V M I R R I A W Y — R I — — L1-07 — N — W V A I H P I A R R V R — S Q — R L1-09 — A — M C G F A S M Q C I L L — L K — — L1-20 M Q — M F A W V L — N A T W K — H G S — L1-22 M — T Y C A I K N R Q R V F M — S L S — L1-24 — N S M L A V T S I R R T V R — K L — — L1-28 — A — M W A W P V S R V T T K — W L — — L1-29 M Q T M W — W P M W — C N S R — W S — — L1-31 — A — M M — A V R V R H W I M — Y Y — — L1-38 A — — M W A W T M W R T M R W — L G — — L1-44 — A — Y Y A V  A — V K A G W S A V A — —

The initial screenings of library 1 also detected library members having reverse repressor activity (SEQ ID NO: 1206-1213), wherein the polypeptide was bound to the operator in the presence of SU ligand. These hits showed β-galactosidase expression without SU ligand, which was substantially reduced upon addition of the ligand, for example thifensulfuron. These hits were subsequently screened in the same plate assay format as described above with the panel of nine sulfonylurea (SU) compounds registered for commercial use (Table 3), wherein 8 hits were found to respond significantly to other SU ligands (Table 6).

TABLE 6 Inducer clone Blank Ts Ms Sm Es Tb Ci Ns Rs Cs atc L1-18 1.34 1.13 0.79 0.94 0.37 1.65 0.36 1.44 2.55 1.22 2.35 L1-21 2.88 0.79 0.89 2.39 0.61 2.13 0.07 2.74 2.31 0.89 2.81 L1-25 1.17 0.64 0.32 0.63 0.13 1.72 0.11 1.21 1.08 0.28 1.22 L1-33 7.59 5.51 4.29 5.02 2.11 4.71 0.76 5.34 10.32 3.74 8.25 L1-34 2.37 2.97 1.47 2.00 1.33 2.26 0.43 2.91 2.30 0.85 3.68 L1-36 1.52 0.48 0.38 0.50 0.20 0.57 0.21 1.81 1.84 0.24 1.70 L1-39 3.65 1.42 0.75 0.91 0.60 0.97 0.49 3.03 4.72 0.89 4.92 L1-41 4.05 1.46 0.56 0.67 0.18 1.41 0.39 2.75 4.05 0.61 4.21 TetR 0.00 0.08 0.08 0.23 0.06 0.13 0.18 0.18 0.20 0.15 10.45

The amino acid substitutions for these eight reverse repressor hits (SEQ ID NO: 1206-1213 encoded by SEQ ID NO: 1214-1221) are summarized in Table 7. The sequences are compared to wild type TetR(B) and only positions having differences are shown using the numbering according to TetR(B) (e.g., SEQ ID NO: 1). A dash in the alignment indicates no change relative to wt TetR ligand binding domain.

TABLE 7 Clone 60 63 64 82 84 86 100 104 105 113 116 121 134 138 139 147 151 163 174 177 205 206 TetR wt L H H N K F H R P L Q C L S G H E H T I F S G SU-TetR-18 — — L — — M W G F K R — I R S R Q P — V — — E SU-TetR-21 — — A — — — C A G — C — R — V C F M — A L — — SU-TetR-25 — — A T — M L A T — L Y W Q W R I T — V K T — SU-TetR-33 — — A N — M Q A A — K — H — T Q R G — R R — — SU-TetR-34 A — N A R M Y A R T V — V R P R L R — R T — — SU-TetR-36 A — — A — M R A W H V — — K S G K M — T V — — SU-TetR-39 M — Q T — Y I — W R V — W A — P R R — L M — — SU-TetR-41 — N Q — — W M — N A G — C R W T D T S M K — — E. Correlation of First Round Shuffling Results with the Structural Model

Significant enrichment occurred at most library positions, where enrichment includes biases favoring particular amino acids and biases disfavoring particular amino acids. The initial screening involved two stages to identify both repressor and de-repressor functions. Enrichment occurred in both stages of screening. In the first stage, positions were enriched by the selection for “apo repressors', that is, proteins that repress gene transcription in the absence of ligand. In the second stage, positions were enriched by the selection for “activators”, that is, proteins that allow gene transcription in the presence of ligand. Positions may be enriched by either selection criterion, by both criteria, or by neither. The first-round screening results for repressor activity are summarized below:

Amino Acid Bias Observed Position Apo repressor SU Induction Both 60 L (not K) 64 Q, N (not L, A) 82 N (not A, T) A (not N, S) 86 (not M) M (not W) 100 R (not K, Q) C, W (not H, K, Q) 104 G A 105 C, G, L, V (not H, K) L, W (not G, S) L 113 A (not G, P) A, I (not D, G) A 116 (not GL) M, V (not A, R) 134 M, S I, R, W (not G) 135 K, R (not H, S) Q, R (not A, T) R 138 (not T) A, C, R, V (not L, P, Q, T) 139 R (not H) T (not L, P) 147 (not A, C) R, W (not A, S) 151 R (not C, G, Q) M, R (not V) R 174 V (not L, R) W (not F, L) 177 T (not S) K, L (not P, T)

Enrichment at the activator level was consistent with the computational model of SU binding: sterically-selected positions (e.g., 60, 86, 104, 105, 113, 138, 139) occurred in closest proximity to the modeled ligand, electrostatically-selected positions (e.g., 135, 147, 151, 177) occurred near the modeled sulfonyl moiety, and aromatically-selected positions (e.g., 100, 105, 147, 174) were modeled to form aromatic stacking interactions with the planar ring structures in thifensulfuron. Enrichment at the apo repressor level was consistent with the predicted mode of DNA binding: enriched positions were modeled to be capable of modulating association of the repressor protein with the DNA operator sequence.

In the case of the SU induction screen, enrichment was evidenced by both over-represented amino acids that were modeled to form favorable interactions with the ligand (e.g., methionine (M) and valine (V) at position 116 were modeled to pack well against the triazine ring of the SU molecule) and by under-represented amino acids that were modeled to produce unfavorable interactions with the ligand (e.g., tryptophan (‘W’) at position 86 was modeled to be too large to accommodate ligand in binding pocket). In the case of the apo repressor, enrichment took the form both of over-represented amino acids that were modeled to give rise to a functional repressor conformation capable of binding the DNA operator sequence in the absence of ligand (e.g., alanine (‘A’) at position 113, which maintains the structural integrity of this α-helix) and of under-represented amino acids that were modeled to disrupt the actively repressing conformation in the absence of ligand (e.g., glycine and proline (R) at position 113, which reduce the structural integrity of this α-helix).

Results from different rounds of screening and selection may produce altered enrichments at some positions, as the result of interactions with other amino acids selected, or with the small molecule. Enriched sequences only demonstrate that side-chains can contribute to active inducers, and do not rule out any amino acids. Thus, selected hits are likely to represent only a subset of possible active sequences. A variety of possible ligand-binding modes and protein interactions may be possible for the same SU molecule, and thus enrichment of several types of side-chains at a specific position may represent multiple populations of active proteins. Computational modeling of the enriched sequences is useful insofar as it enables the prioritization of amino acid diversity for rounds of screening and selection.

Altogether, these enrichment results support the overall computational model and facilitated additional design. Several positions which were constructed as fully-degenerate codons (all 20 amino acids) returned first-round screening results consistent with the suggested computational model. For example, computational modeling suggested that the aromatic side-chains W, Y and F at position 100 would favor SU binding. The first-round library was screened with a degenerate codon at this position, and the amino acids W, Y and F were significantly enriched. Designed libraries allow sequence diversity to be narrowed at library positions, with an emphasis on decreasing diversity at coupled positions such that fully degenerate codons may be avoided. Additionally, more positions could be recruited for diversification to achieve greater coverage of a higher-quality, more focused sequence library. This allows construction of a library with sufficiently few members to screen with good coverage, yet sufficient diversity to discover sequences with detectable activity. Such sequences may then be improved by introducing more diversity at library positions, with a screen or selection choosing optimal clones, independent of model predictions. In this way, the combination of computational modeling and directed evolution allows the generation of engineered sequences unlikely to be discovered by either technique separately.

F Second-Round Shuffling

The original library was designed to thifensulfuron, but once induction activity was established with other SU compounds having potentially better soil and in planta stability properties than the original ligand, the evolution process was re-directed towards these alternative ligands. Of particular interest were herbicides metsulfuron, sulfometuron, ethametsulfuron and chlorsulfuron. For this objective, parental clones L1-9, -22, -29 and -44 were chosen for further shuffling. Clone L1-9 has strong activity on both ethametsulfuron and chlorsulfuron; clone L1-22 has strong sulfometuron activity; clone L1-29 has moderate metsulfuron activity; and clone L1-44 has moderate activity on metsulfuron, ethametsulfuron and chlorsulfuron (Table 4). No clones found in the initial screen were exceptionally reactive to metsulfuron. These four clones were also chosen due to their relatively strong repressor activity, showing low β-gal background activity without inducer. Strong repressor activity is important for establishing a system which is both highly sensitive to the presence od inducer, and tightly off in the absence of inducer.

Based on the sequence information from parental clones L1-9, -22, -29 and -44, two second round libraries were designed, constructed and screened. The first library, L2, consisted of a ‘family’ shuffle whereby the amino acid diversity between the selected parental clones was varied using synthetic assembly of oligonucleotides to find clones improved in responsiveness to any of the four new target ligands. A summary of the diversity used and the resulting hit sequences for library L2 is shown in Table 8.

TABLE 8 Amino acid residue position Clone 60 64 82 86 100 104 105 113 116 134 135 wt L H N F H R P L Q L S Parents L1-9 — A — M C G F A S M Q L1-22 M — T Y C A I K N R Q L1-29 M Q T M W — W P M W — L1-44 — A — Y Y A V A — V K Hits L2-2 — Q — M C — F K — V — L2-9 M Q — M Y — W A — W — L2-10 — A — M W G W K M M — L2-13 — Q — M C — W A — W Q L2-14 M A — M C — W A M V — L2-18 M Q T M W — W A — M — L1-45 A Q — W W G L P V T Q Unselected random random random random W > C, Y R >> G, A W > V > I, F random random random S >> Q, K frequency Amino acid residue position Inducer Clone 138 139 147 151 164 174 177 203 preference wt G H E H D I F C atc Parents L1-9 C I L L — L K — 4, 9 (weak) L1-22 R V F M — S L S 3 L1-29 C N S R — W S — 9 (weak) L1-44 A G W S A V A — 9 (weak) Hits L2-2 R I W M — W L — 4 (inverse) L2-9 A I W S — S K — 9 (leaky) L2-10 R I L L — W K — 4 (leaky) L2-13 R I S M — V K — 9 L2-14 R V F S A L K — 9 L2-18 R N F L A W K — 9 L1-45 R — G R — A L — 3, 4 Unselected A >> C, R G, N > V > I random random random random random C >> S frequency

The oligonucleotides used to construct the library are shown in Table 9. The L2 oligonucleotides were assembled, cloned and screened as per the protocol described for library L1 except that each ligand was tested at 2 ppm to increase the stringency of the assay, which is a 10-fold reduction from 1st round library screening concentration.

TABLE 9 SEQ Oligo Sequence ID L2:01 TATTGGCATGTAAAAAATAAGCGAGCTCTGCTCGACGCCT 885 TA L2:02 GCCATTGAGATGWTGGATAGGCACCASACTCACTTTTGCC 886 CT L2:03 GCCATTGAGATGWTGGATAGGCACGCAACTCACTTTTGCC 887 CT L2:04 TTAGAAGGGGAAAGCTGGCAAGATTTTTTACGTAATAMTG 888 CT L2:05 AAAAGTTACAGATGTGCTTTACTAAGTCATCGCGATGGAG 889 CA L2:06 AAAAGTATGAGATGTGCTTTACTAAGTCATCGCGATGGAG 890 CA L2:07 AAAGTATRTTTAGGTACACGCDTCACAGAAAAACAGTATG 891 AA L2:08 AAAGTATRTTTAGGTACACGCTGGACAGAAAAACAGTATG 892 AA L2:09 AAAGTATRTTTAGGTACAGSTDTCACAGAAAAACAGTATG 893 AA L2:10 AAAGTATRTTTAGGTACAGSTTGGACAGAAAAACAGTATG 894 AA L2:11 AAAGTATGGTTAGGTACACGCDTCACAGAAAAACAGTATG 895 AA L2:12 AAAGTATGGTTAGGTACACGCTGGACAGAAAAACAGTATG 896 AA L2:13 AAAGTATGGTTAGGTACAGSTDTCACAGAAAAACAGTATG 897 AA L2:14 AAAGTATGGTTAGGTACAGSTTGGACAGAAAAACAGTATG 898 AA L2:15 ACTAAAGAAAATARCTTAGCCTTTTTATGCCAACAAGGTT 899 TT L2:16 ACTAAAGAAAATCAATTAGCCTTTTTATGCCAACAAGGTT 900 TT L2:17 ACTAAAGAAAATATGTTAGCCTTTTTATGCCAACAAGGTT 901 TT L2:18 ACTSCTGAAAATARCTTAGCCTTTTTATGCCAACAAGGTT 902 TT L2:19 ACTSCTGAAAATCAATTAGCCTTTTTATGCCAACAAGGTT 903 TT L2:20 ACTSCTGAAAATATGTTAGCCTTTTTATGCCAACAAGGTT 904 TT L2:21 TCACTAGAGAATGCATTATATGCARTGAGTGCTGTGGCTA 905 WT L2:22 TCACTAGAGAATGCATTATATGCARTGAGTGCTGTGGCTG 906 KT L2:23 TCACTAGAGAATGCATTATATGCARTGAGTGCTGTGYGCA 907 WT L2:24 TCACTAGAGAATGCATTATATGCARTGAGTGCTGTGYGCG 908 KT L2:25 TCACTAGAGAATGCATTATATGCARTGMAAGCTGTGGCTA 909 WT L2:26 TCACTAGAGAATGCATTATATGCARTGMAAGCTGTGGCTG 910 KT L2:27 TCACTAGAGAATGCATTATATGCARTGMAAGCTGTGYGCA 911 WT L2:28 TCACTAGAGAATGCATTATATGCARTGMAAGCTGTGYGCG 912 KT L2:29 TCACTAGAGAATGCATTATATGCAWGGAGTGCTGTGGCTA 913 WT L2:30 TCACTAGAGAATGCATTATATGCAWGGAGTGCTGTGGCTG 914 KT L2:31 TCACTAGAGAATGCATTATATGCAWGGAGTGCTGTGYGCA 915 WT L2:32 TCACTAGAGAATGCATTATATGCAWGGAGTGCTGTGYGCG 916 KT L2:33 TCACTAGAGAATGCATTATATGCAWGGMAAGCTGTGGCTA 917 WT L2:34 TCACTAGAGAATGCATTATATGCAWGGMAAGCTGTGGCTG 918 KT L2:35 TCACTAGAGAATGCATTATATGCAWGGMAAGCTGTGYGCA 919 WT L2:36 TCACTAGAGAATGCATTATATGCAWGGMAAGCTGTGYGCG 920 KT L2:37 TTTACTTTAGGTTGCGTATTGTKGGATCAAGAGAGMCAAG 921 TC L2:38 TTTACTTTAGGTTGCGTATTGTKGGATCAAGAGMTGCAAG 922 TC L2:39 TTTACTTTAGGTTGCGTATTGTYTGATCAAGAGAGMCAAG 923 TC L2:40 TTTACTTTAGGTTGCGTATTGTYTGATCAAGAGMTGCAAG 924 TC L2:41 GCTAAAGAAGAAAGGGAAACACCTACTACTGMTAGTATGC 925 CG L2:42 CCATTATTACGACAAGCTAGTGAATTATTGGATCACCAAG 926 GT L2:43 CCATTATTACGACAAGCTAGTGAATTAKCAGATCACCAAG 927 GT L2:44 CCATTATTACGACAAGCTAGTGAATTAAAGGATCACCAAG 928 GT L2:45 CCATTATTACGACAAGCTTKGGAATTATTGGATCACCAAG 929 GT L2:46 CCATTATTACGACAAGCTTKGGAATTAKCAGATCACCAAG 930 GT L2:47 CCATTATTACGACAAGCTTKGGAATTAAAGGATCACCAAG 931 GT L2:48 CCATTATTACGACAAGCTGTAGAATTATTGGATCACCAAG 932 GT L2:49 CCATTATTACGACAAGCTGTAGAATTAKCAGATCACCAAG 933 GT L2:50 CCATTATTACGACAAGCTGTAGAATTAAAGGATCACCAAG 934 GT L2:51 GCAGAGCCAGCCTTCTTATTCGGCCTTGAATTGATCATAT 935 GC L2:52 GGATTAGAAAAACAACTTAAATSCGAAAGTGGGTCTTAA 936 L2:53 CCTATCCAWCATCTCAATGGCTAAGGCGTCGAGCAGAGCT 937 CG L2:54 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGTSTGG 938 TG L2:55 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGTTGCG 939 TG L2:56 TAAAGCACATCTGTAACTTTTAGCAKTATTACGTAAAAAA 940 TC L2:57 TAAAGCACATCTCATACTTTTAGCAKTATTACGTAAAAAA 941 TC L2:58 GCGTGTACCTAAAYATACTTTTGCTCCATCGCGATGACTT 942 AG L2:59 ASCTGTACCTAAAYATACTTTTGCTCCATCGCGATGACTT 943 AG L2:60 GCGTGTACCTAACCATACTTTTGCTCCATCGCGATGACTT 944 AG L2:61 ASCTGTACCTAACCATACTTTTGCTCCATCGCGATGACTT 945 AG L2:62 GGCTAAGYTATTTTCTTTAGTTTCATACTGTTTTTCTGTG 946 AH L2:63 GGCTAATTGATTTTCTTTAGTTTCATACTGTTTTTCTGTG 947 AH L2:64 GGCTAACATATTTTCTTTAGTTTCATACTGTTTTTCTGTG 948 AH L2:65 GGCTAAGYTATTTTCAGSAGTTTCATACTGTTTTTCTGTG 949 AH L2:66 GGCTAATTGATTTTCAGSAGTTTCATACTGTTTTTCTGTG 950 AH L2:67 GGCTAACATATTTTCAGSAGTTTCATACTGTTTTTCTGTG 951 AH L2:68 GGCTAAGYTATTTTCTTTAGTTTCATACTGTTTTTCTGTC 952 CA L2:69 GGCTAATTGATTTTCTTTAGTTTCATACTGTTTTTCTGTC 953 CA L2:70 GGCTAACATATTTTCTTTAGTTTCATACTGTTTTTCTGTC 954 CA L2:71 GGCTAAGYTATTTTCAGSAGTTTCATACTGTTTTTCTGTC 955 CA L2:72 GGCTAATTGATTTTCAGSAGTTTCATACTGTTTTTCTGTC 956 CA L2:73 GGCTAACATATTTTCAGSAGTTTCATACTGTTTTTCTGTC 957 CA L2:74 ATATAATGCATTCTCTAGTGAAAAACCTTGTTGGCATAAA 958 AA L2:75 CAATACGCAACCTAAAGTAAAAWTAGCCACAGCACTCAYT 959 GC L2:76 CAATACGCAACCTAAAGTAAAAMCAGCCACAGCACTCAYT 960 GC L2:77 CAATACGCAACCTAAAGTAAAAWTGCRCACAGCACTCAYT 961 GC L2:78 CAATACGCAACCTAAAGTAAAAMCGCRCACAGCACTCAYT 962 GC L2:79 CAATACGCAACCTAAAGTAAAAWTAGCCACAGCTTKCAYT 963 GC L2:80 CAATACGCAACCTAAAGTAAAAMCAGCCACAGCTTKCAYT 964 GC L2:81 CAATACGCAACCTAAAGTAAAAWTGCRCACAGCTTKCAYT 965 GC L2:82 CAATACGCAACCTAAAGTAAAAMCGCRCACAGCTTKCAYT 966 GC L2:83 CAATACGCAACCTAAAGTAAAAWTAGCCACAGCACTCCWT 967 GC L2:84 CAATACGCAACCTAAAGTAAAAMCAGCCACAGCACTCCWT 968 GC L2:85 CAATACGCAACCTAAAGTAAAAWTGCRCACAGCACTCCWT 969 GC L2:86 CAATACGCAACCTAAAGTAAAAMCGCRCACAGCACTCCWT 970 GC L2:87 CAATACGCAACCTAAAGTAAAAWTAGCCACAGCTTKCCWT 971 GC L2:88 CAATACGCAACCTAAAGTAAAAMCAGCCACAGCTTKCCWT 972 GC L2:89 CAATACGCAACCTAAAGTAAAAWTGCRCACAGCTTKCCWT 973 GC L2:90 CAATACGCAACCTAAAGTAAAAMCGCRCACAGCTTKCCWT 974 GC L2:91 TGTTTCCCTTTCTTCTTTAGCGACTTGKCTCTCTTGATCC 975 MA L2:92 TGTTTCCCTTTCTTCTTTAGCGACTTGCAKCTCTTGATCC 976 MA L2:93 TGTTTCCCTTTCTTCTTTAGCGACTTGKCTCTCTTGATCA 977 RA L2:94 TGTTTCCCTTTCTTCTTTAGCGACTTGCAKCTCTTGATCA 978 RA L2:95 ACTAGCTTGTCGTAATAATGGCGGCATACTAKCAGTAGTA 979 GG L2:96 CMAAGCTTGTCGTAATAATGGCGGCATACTAKCAGTAGTA 980 GG L2:97 TACAGCTTGTCGTAATAATGGCGGCATACTAKCAGTAGTA 981 GG L2:98 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCCAATAAT 982 TC L2:99 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCTGMTAAT 983 TC L2:100 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCCTTTAAT 984 TC L2:101 TTTAAGTTGTTTTTCTAATCCGCATATGATCAATTCAAGG 985 CC L2:102 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCGSA 986 G. Screening Results for Library L2

Nearly 8,000 colonies arising from the repressor prescreen were subjected to the activation screen on M9 assay medium containing potential inducers ethametsulfuron, sulfometuron, metsulfuron or chlorsulfuron at 2 ppm. After 48 hours of incubation at 30° C. the plates were analyzed. Twelve putative hits from these plates were re-arrayed into 96-well format and retested on the same set of media (Table 10). Only clone L2-14 had a strong induction response and tight regulation to any of the inducers at this lower 2 ppm dose, wherein it had a strong response to Cs and low background without inducer. Clone L2-18 had a moderate response to this ligand and low background. Clone L2-9 also responded well to Cs, but had higher background activity without inducer. No isolates showed a significant response to metsulfuron. An unexpected observation was that parent clone L1-9 has sensitivity to 2 ppm Es. Sequence analysis of the hit clones from library 2 (Table 6) indicates that F86M, G138R and F177K were preferred substitutions in the responding hits. This is especially striking at position 138 where A is far over represented in the unselected population and yet five clones have R at this position while only one has alanine. R105W could also be important, but in the random sequence population W105 was already biased over C or Y.

TABLE 10 Inducer Sample No inducer Ms Sm Es Cs L1 parents L1-9 0.9 0.9 0.9 14.8 2.2 L1-22 0.2 0.2 1.8 0.2 0.2 L1-29 0.1 0.3 0.2 0.3 0.2 L1-44 0.6 0.5 0.6 1.0 1.9 L2 hits L2-9 2.2 4.2 6.3 5.0 14.0 L2-10 1.3 1.1 1.7 7.7 1.7 L2-13 1.8 1.9 2.4 2.0 8.4 L2-14 0.5 1.0 0.9 0.9 17.0 L2-18 0.3 0.1 0.2 0.3 4.6 TetR 0.1 0.0 0.1 0.1 0.1 H. Second Round Library L4 Assembly

Another second round library, L4, was created from synthetic oligonucleotides using clone L1-9 as the template and injecting novel amino acid diversity into the sequence based on phylogenetic comparison of 34 TetR and related molecules. A multiple sequence alignment of SEQ ID NO: 1 and SEQ ID NO: 402-433 generated using GCG Seq Web PILEUP (Accelrys, San Diego, Calif.) under default parameters of gap weight=8, gap length weight=2, and the BLOSUM62 matrix is shown below:

1                                                   50 ZP_01558383 ~~~mkdtg.a rltrdtvmra aldllnevgi dglstrrlae rlgvqsptly YP_772551 ~~~mkdts.t rltrdtvmra aldllnevgi dglstrrlae rlgvqsptly YP_620166 ~~~mkdtg.t rltrdtvlra alnlldevgi dglstrrlae rlgvqsptly EAY62734 miemkdtg.a rltrdtvlra alnlldevgi dglstrrlae rlgvqsptly YP_368094 ~~~mkdtg.a rltrdtvlra alelldevgi dglstrklae rlgvqsptly AAP93923 ~mseknta.a rltretvlrg alallddigi dalstrrlaq hlgvqsptly AAW66496 ~mskkdiapq rltreivlrt aldmlneegi dsittrklaq rlgiksptly CAA24908 ~~~~~~~~mt klqpntvira aldllnevgv dglttrklae rlgvqqpaly P03038 ~~~~~~~~mt klqpntvira aldllnevgv dglttrklae rlgvqqpaly ABS19067 ~~~~~~~~mi klqpntvirv aldllnevgv ealttrklak rlgvqqpaly NP_387462 ~~~~~~~~mn klqreavirt alellndvgm eglttrrlae rlgvqqpaly NP_387455 ~~~~~~~~mk klqreavirt alellndvgm eglttrrlae rlgvqqpaly AAR96033 ~~~~~~~~mn klqreavirt alellndvgm eglttrrlae rlgvqqpaly NP_511232 ~~~~~~~~mn klqreavirt alellndvgm eglttrrlae rlgvqqpaly AAW83818 ~~~~~~~~mt klqpntvira aldllnevgv dglttrklae rlgvqqpaly AAD25094 ~~~~~~~~mt kldkgtviaa alellnevgm dslttrklae rlkvqqpaly ABO14708 ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~ly P51560 ~~~~~~~~mt kldkgtviaa glellnevgm dslttrklae rlkvqqpaly AAD25537 ~~~~~~~~mt kldkgtviaa alellnevgm dslttrklae rlrvqqpaly YP_001220607 ~~~~~~~~mt kldretviqa alellnevgv dnlttrklae rlkvqqpaly YP_001370475 ~~~~mvsala klhrdaviqt alellnevge eglttrrlae rlgvqqpaly P21337 ~~~~~~~~ma rlslddvism altlldsegl eglttrklaq slkieqptly AAA98409 ~~~~~~~~ma rlslddvism altlldsegl eglttrklaq slkieqptly CAC81917 ~~~~~~~~ma rlslddvism altlldregl eglttrnvaq slkieqptly P51561 ~~~~~~~~ma kldkeqvidd alillnevgi eglttrnvaq kigveqptly ZP_00132379 ~~~~~~~~ma kldkeqvidn alillnevgi eglttrklaq kigveqptly AAD12754 ~~~~~~~~ma kldkeqvidn alillnevgm eglttrklaq klgveqptly P04483 ~~~~~~~~ms rldkskvins alellnevgi eglttrklaq klgveqptly A26948 ~~~~~~~~ms rldkskvins alellnevgi eglttrklaq klgveqptly CAC80726 ~~~~~~~mma rldkkrvies alalldevgm eglttrklaq klnieqpsly P0ACT4 ~~~~~~~~MA RLNRESVIDA ALELLNETGI DGLTTRKLAQ KLGIEQPTLY ZP_01567051 ~~~~~~~~ma kirrdeivda alalldeqgl dalttrrlaq rlgvesaaly NP_824556 ~~~mvtqrsp kldkkqvvet alrllneagl dgltlraiak elnvqapaly 51                                                 100 ZP_01558383 whfrnkaell damaeaimle rhgaslprpg dawdawllen arsfrralla YP_772551 whfrnkaell damaeaimle rhgaslprpg dtwdawllen argfrralla YP_620166 whfrnkaell damaeaimle rhgeslprpg dvwdvwlaen arsfrralla EAY62734 whfrnkaell damaeaimle rhgeslprpg dvwdvwlaen arsfrralla YP_368094 whfrnkgell damaeaimle rhdaslprpg eawdawlldn arsfrralla AAP93923 whfknkaell kamaetimld .hreevpadm p.wqawvtan ainfrralla AAW66496 whfknksllm eamaetiine hhlvslpidg mtwqdwllan svsfrralla CAA24908 whfrnkrall dalaeamlae nhstsvprad ddwrsfltgn arsfrqalla P03038 whfrnkrall dalaeamlae nhthsvprad ddwrsflign arsfrqalla ABS19067 whfrnkrall dalaeamlae nhthsvprvd ddwrsflign arsfrqalla NP_387462 whfknkrall dalaeamlti nhthstprdd ddwrsflkgn acsfrralla NP_387455 whfrnkrall dalaeamlti nhthstprde ddwrsflkgn acsfrralla AAR96033 whfknkrall dalaeamlti nhthstprdd ddwrsflkgn acsfrralla NP_511232 whfknkrall dalaeamlti nhthstprdd ddwrsflkgn acsfrralla AAW83818 whfrnkrall dalaeamlae nhthsvprad ddwrsflkgn acsfrralla AAD25094 whfqnkrall dalaeamlae rhtrslpeen edwrvflken alsfrtalls ABO14708 whfqnkrall dalaeamlae rhtrslpeen edwrvflken alsfrtalls P51560 whfqnkrall dalpeamlre rhtrslpeen edwrvflken alsfrtalls AAD25537 whfpskrall dalaeamlte rhtrslpeen edwrvflken alsfrkalls YP_001220607 whfrnkrall dalseamlek nhtrtvpqtg edwrvflken alsfrsalls YP_001370475 whfknkrvll dalaetilae hhdhalprag enwrhflien ahsfrrallt P21337 whvrnkqtlm nmlseailak hhtrsaplpt eswqqflqen alsfrkallv AAA98409 whlrnkqtlm nmlseailak hhtrsaplpt eswqqflqen alsfrkallv CAC81917 whvrnkqtlm nmlseailak hhtrsvplpt eswqqflqen alsfrkallv P51561 whvknkrall dalaetilqk hhhhvlplpn etwqdflrnn aksfrqallm ZP_00132379 whvknkrall dalaetilqk hhhhvlplpn etwqdflrnn aksfrqallm AAD12754 whvknkrall dalaetilqk hhhhvlplan eswqdflrnn aksfrqallm P04483 whvknkrall dalaiemldr hhthfcpleg eswqdflrnn aksfrcalls A26948 whvknkrall dalaiemldr hhthfcpleg eswqdflrnn aksfrcalls CAC80726 whvknkrall dalsveillr hhdhfqpqkg eywadflren aksfrralls P0ACT4 WHVKNKRALL DALAVEILAR HHDYSLPAAG ESWQSFLRNN AMSFRRALLR ZP_01567051 whyrdksvll aemaavalar hhtldvpadt aqwdawfadn arsfrralla NP_824556 whfknkqall dematemyrr mtegahlapg aswqerllhg nralrtallg 101                                                150 ZP_01558383 yrdgarlhag tr.prtlhfg sierkvalla eagfapdeav dvmyalgrfv YP_772551 yrdgarlhag tr.prtlhfd sierkvalla dagfapdeav dvmyalgrfv YP_620166 yrdgarlhag tr.pralhfs sierkvallg eagfkpdeav dvmvaigrfv EAY62734 yrdgarlhag tr.pralhfs sierkvallg eagfkpdeav dvmvaigrfv YP_368094 yrdgarlhag tr.pralhfs sierkvallg dagfapdeav dvmyalgrfv AAP93923 yrdgarlhag tr.pqepqfa iieakvallc ragftpehav nllfavgrfv AAW66496 yrdgarlhar ts.psqghfn tieaqvalls hagfspveav allmtlgrfi CAA24908 yrdgarihag tr.pgapqme tadaqlrflc eagfsagdav nalmtisyft P03038 yrdgarihag tr.pgapqme tadaqlrflc eagfsagdav nalmtisyft ABS19067 yrdgarihag tr.pgapqme vvdaqlrflc eagfsawdav nalmtisyft NP_387462 yrdgarihag tr.saapqme kadaqlrflc dagfsagdat yalmaisyft NP_387455 yrdgarihag tr.paapqme kadaqlrflc dagflagdat yalmaisyft AAR96033 yrdgarihag tr.paapqme kadaqlrflc dagfsagdat yalmaisyft NP_511232 yrdgarihag tr.paapqme kadaqlrflc dagfsagdat yalmaisyft AAW83818 yrdgarihag tr.paapqme kadaqlrflc dagfsagdat yalmaisyft AAD25094 yrdgarihag tr.ptepnfg taetqirflc aegfcpkrav walravshyv ABO14708 yrdgarihag tr.ptepnfg taetqirflc aegfcpkrav walravshyv P51560 yrdgarihag tr.ptepnfg taetqirflc aegfcpkrav walravshyv AAD25537 yrdgarihag tr.ptephyg taeaqirflc tagfspkrav walwavshyv YP_001220607 yrdgarihag tr.ptsaqye rvekqirflc esgfeqpdav ralvivshyt YP_001370475 yrdgahihag tr.pnnnqag qaetqiefli qagftpanaa raliaishyv P21337 hrdgarlhig ts.ptppqfe qaeaqlrclc dagfsveeal filqsishft AAA98409 hrdgarlhig ts.ptppqfe qaeaqlrclc dagfsveeal filqsishft CAC81917 hrdgarlhig ts.ptppqfe qaeaqlrclc dagfsveeal filqsishft P51561 yrdggkihag tr.psesqfe tseqqlqflc dagfslsqav yalssiahft ZP_00132379 yrdggkihag tr.psesqfe tseqqlqflc dagfslsqav yalssiahft AAD12754 yrdggkihag tr.psanqfe tseqqlqflc dagftltqav yalssiahft P04483 hrdgakvhlg tr.ptekqye tlenqlaflc qqgfslenal yalsavghft A26948 hrdgakvhlg tr.ptekqye tlenqlafya nkvfh~~~~~ ~~~~~~~~~~ CAC80726 hrdaakihlg tr.pspeqfe tveaqlaflc eqgfsleeal ytlgvvshft P0ACT4 YRDGAKVHLG TR.PDEKQYD TVETQLRFMT ENGFSLRDGL YAISAVSHFT ZP_01567051 hrdgarlhag st.pdldave rirpkiaylv raglteqeag mamlaagqft NP_824556 yrdgakvfsg srftgtehav qleaslrslv eagfdlpqav ratstayfft 151                                                200 ZP_01558383 vgwvleeqae aeretd.... .ttlpdtaeh p..llaqgwa alrerggdea YP_772551 vgwvleeqae aeretd.... .ttlpdtaeh p..llaqgwt alrerggdea YP_620166 vgwvleeqar pdgdtd.... .allpdaaey p..lfaqgwa alrersgdea EAY62734 vgwvleeqar pdgdad.... .allpdaaey p..lfakgwa alrersgdea YP_368094 vgwvleeqae ssdeaa.... .aplpdaaey p..llakgwa alrgrsgdda AAP93923 vgwvleeqqm qpdda..... .lneadrrry p..llcggwe klqdkgadal AAW66496 vgwvleeqqe eirsdp.... .pfeadptiy p..lmlqgvn tlqnmnaddi CAA24908 vgavleeqag dsesgergg. ..tveqapls p..llraaid afdeagpdaa P03038 vgavleeqag dsdagergg. ..tveqapls p..llraaid afdeagpdaa ABS19067 vgavleeqag dsdagergg. ..tieqa... p..llravid tfdeagpdav NP_387462 vgavleqqas eadaeerged qlttsastmp a..rlqsamk ivyeggpdaa NP_387455 vgavleqqas eadaeerged qlttsastmp a..rlqsamk ivyeggpdaa AAR96033 vgavleqqas eadaeerged qlttsastmp a..rlqsamk ivyeggpdaa NP_511232 vgavleqqas eadaeerged qlttsastmp a..rlqsamk ivyeggpdaa AAW83818 vgavleqqas eadaeerged qlttsastmp a..rlqsamk ivyeggpdaa AAD25094 vgsvleqqas ..dadervpd rpdvseqaps s..flhdlfh eletdgmdaa ABO14708 vgsvleqqas ..dadervpd rpdvseqaps s..flhdlfh eletdgmdaa P51560 vgsvleqqas ..dadervpd rpdvseqaps s..flhvlfh eletdgmdaa AAD25537 vgsvleqqas ..nandrmsd ksdvseqaps s..flhdlfh eletdgmdap YP_001220607 tgsvseqqaa ledsserkqa skeapaq.ps q..flshafd tfdaegadfa YP_001370475 vgsaleqqa. ..dihesvpg ..davsitat s..eiaqaia ildadgaenl P21337 lgavleeq.. atnqien..n hvid...aap p..llqeafn iqartsaema AAA98409 lgavleeq.. atnqien..n hvid...aap p..llqeafn iqartsaema CAC81917 lgavleeq.. atnptey..n tvmd...avp p..llqeafn vqtrttaeta P51561 lgsvletqeh qesqker..e kvetdtvayp p..lltqava imdsdngdaa ZP_00132379 lgsvletqeh qesqker..e kvetdtvayp p..lltqava imdsdngdaa AAD12754 lgsvletqeh qesqker..e kvpkteinyp p..lltqaid imdsdngeaa P04483 lgcvledqeh qvakeer..e tpttdsm..p p..llrqaie lfdhqgaepa A26948 ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ CAC80726 lgsvleerey leamrdd..d paihaam..p p..lltkale imeqdtgekp P0ACT4 LGAVLEQQEH TAALTDR..P AAPDENL..P P..LLREALQ IMDSDDGEQA ZP_01567051 igcvleqqaa qgrgaeepar rdaaddrp.. .....rtsga alapidpgva NP_824556 lgfvteeqgv eplpgerreg ydvderaarm adfplaaaag aeifqnyeeg 201                                  237 ZP_01558383 fergvalivd gararla.ar rrgg~~~~~~ ~~~~~~~ YP_772551 fergvalivd gararla.ar qrgg~~~~~~ ~~~~~~~ YP_620166 fergiawivd gararla.ar rag~~~~~~~ ~~~~~~~ EAY62734 fergiawivd gararla.ar rag~~~~~~~ ~~~~~~~ YP_368094 fergvawivd gararla.ar erg~~~~~~~ ~~~~~~~ AAP93923 feaglrllvd gaeaaltnan nhgaqs~~~~ ~~~~~~~ AAW66496 fengirmvii gaerqldikm qt~~~~~~~~ ~~~~~~~ CAA24908 feqglavivd glakrrlvvr nvegprkgdd ~~~~~~~ P03038 feqglavivd glakrrlvvr nvegprkgdd ~~~~~~~ ABS19067 felglavivd glakrrlvar niqgprkgdd ~~~~~~~ NP_387462 ferglaliig gleqvrlspa sspagrtnlv lalaags NP_387455 ferglaliig gleqvrlspa sspagrtnlv lalaags AAR96033 ferglaliig glersacais ll~~~~~~~~ ~~~~~~~ NP_511232 ferglaliig glekmrlttn dievlknvde ~~~~~~~ AAW83818 ferglaliig glersacais ll~~~~~~~~ ~~~~~~~ AAD25094 fnfgldslia gferlrss.. ttd~~~~~~~ ~~~~~~~ ABO14708 fnfgldslia gferlrss.. ttd~~~~~~~ ~~~~~~~ P51560 fnfgldslia gferlraavl atd~~~~~~~ ~~~~~~~ AAD25537 fnfgldslia gfeqlrls.. ttd~~~~~~~ ~~~~~~~ YP_001220607 feygldalis glemkkatk~ ~~~~~~~~~~ ~~~~~~~ YP_001370475 fdfglmllvd glerhrqs~~ ~~~~~~~~~~ ~~~~~~~ P21337 fhfglkslif gfsaqldekk htpiedgnk~ ~~~~~~~ AAA98409 fhfglkslif gfsaqldekk htpiedgnk~ ~~~~~~~ CAC81917 fhfglrsliv gfsaqlde.k ymsiqgnnk~ ~~~~~~~ P51561 flfvldvmis gletvlksak ~~~~~~~~~~ ~~~~~~~ ZP_00132379 flfvldvmis gletvlksak ~~~~~~~~~~ ~~~~~~~ AAD12754 flfvldvmis gletvlnnhh ~~~~~~~~~~ ~~~~~~~ P04483 flfgleliic glekqlkces gs~~~~~~~~ ~~~~~~~ A26948 ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~ CAC80726 flfgleviil gleakqkqkk gnqe~~~~~~ ~~~~~~~ P0ACT4 FLHGLESLIR GFEVQLTALL QIVGGDKLII PFC~~~~ ZP_01567051 fefglglivd glrrrvdra~ ~~~~~~~~~~ ~~~~~~~ NP_824556 feeglrlvia giearygir~ ~~~~~~~~~~ ~~~~~~~

Amino acid positions having relatively conserved amino acid substitutions between family members were considered for harvesting diversity. In addition, positions were chosen for variation based on spacing to limit the number of changes in a pair of overlapping oligonucleotides. A summary of the library is shown in Table 11. The objective of this library was to recover hits improved for reactivity to either ethametsulfuron or chlorsulfuron.

TABLE 11 Residue Position L1-9 Backbone 52 55 62 69 73 76 79 83 85 88 93 96 98 101 102 109 110 114 117 120 Sequence L L R P E Q L A S C H G K L G Q Y E L L Shuffling L L D L A A F A A C H A K I G H F D I L Diversity M M E P D D L N G R Y G R L R N V E L M K E Q V S N S S Q Y R V Y R R S Residue Position L1-9 Backbone 125 129 130 137 140 145 149 162 167 170 175 181 183 189 190 193 197 Sequence F N A V F V Q T P L E G E G L I L Shuffling F D A A F A Q Q P F D G D G I I A Diversity L E G I Y V R T S I E S E V L L F H L L N G V M I N V M V L Q

Assembly of the L4 library synthetic oligonucleotides was done as for the previous libraries, except that two sets of oligonucleotide pools were used. First, multiple oligonucleotides representing diversity at a single oligonucleotide annealing location are pooled (“Group” in Table 12). Next, an equal volume of each group of oligos is pooled to represent the novel L4 diversity. Likewise, oligonucleotides representing the L1-9 backbone sequence were pooled (Table 13). The L4 assembly reaction was carried out by spiking the oligonucleotide diversity pool into the L1-9 backbone pool at an approximately 1:3 ratio.

TABLE 12 SEQ Oligo Sequence Group ID L4:01 TATTGGCATGTAAAAAATAAGCGAGCTCTGWTGGACGCCWTG 1 987 L4:02 TATTGGCATGTAAAGAATAAGVGCGCTCTGWTGGACGCCWTG 1 988 L4:03 GCCATTGAGATGCTCGATARACACGCCACTCACTTTTGCCYC 2 989 L4:04 GCCATTGAGATGCTCGATGAKCACGCCACTCACTTTTGCCYC 2 990 L4:05 TTAGAAGGGGMWAGCTGGCAAGATTTTBTTCGTAATAACGCA 3 991 L4:06 TTAGAAGGGGMWAGCTGGCAAGATTTTBTTCGTAATAACART 3 992 L4:07 TTAGAAGGGGMWAGCTGGAGGGATTTTBTTCGTAATAACGCA 3 993 L4:08 TTAGAAGGGGMWAGCTGGAGGGATTTTBTTCGTAATAACART 3 994 L4:09 TTAGAAGGGGMWAGCTGGGMTGATTTTBTTCGTAATAACGCA 3 995 L4:10 TTAGAAGGGGMWAGCTGGGMTGATTTTBTTCGTAATAACART 3 996 L4:11 AAAARTATGAGAHGTGCTTTACTAAGTYACCGCGATGSAGCA 4 997 L4:12 AAAGSAATGAGAHGTGCTTTACTAAGTYACCGCGATGSAGCA 4 998 L4:13 ARAGTATGCTCCRGGACAGGATTTACAGAAAAACAAKTTGAA 5 999 L4:14 ARAGTATGCTCCRGGACAGGATTTACAGAAAAACAATACGAA 5 1000 L4:15 ARAGTATGCTCCRGGACAGGATTTACAGAAAAAMATKTTGAA 5 1001 L4:16 ARAGTATGCTCCRGGACAGGATTTACAGAAAAAMATTACGAA 5 1002 L4:17 ARAGTATGCMTCRGGACAGGATTTACAGAAAAACAAKTTGAA 5 1003 L4:18 ARAGTATGCMTCRGGACAGGATTTACAGAAAAACAATACGAA 5 1004 L4:19 ARAGTATGCMTCRGGACAGGATTTACAGAAAAAMATKTTGAA 5 1005 L4:20 ARAGTATGCMTCRGGACAGGATTTACAGAAAAAMATTACGAA 5 1006 L4:21 ACTGCTGAMAATTCAVTTGCCTTTMTGTGCCAACAAGGTTTK 6 1007 L4:22 ACTGCTGAMAATTCAVTTGCCTTTTACTGCCAACAAGGTTTK 6 1008 L4:23 ACTGCTAGGAATTCAVTTGCCTTTMTGTGCCAACAAGGTTTK 6 1009 L4:24 ACTGCTAGGAATTCAVTTGCCTTTTACTGCCAACAAGGTTTK 6 1010 L4:25 TCACTAGAGVACGSATTATATGCAATGCAAGCTGCATGTATT 7 1011 L4:26 TCACTAGAGVACGSATTATATGCAATGCAAGCTVTCTGTATT 7 1012 L4:27 TCACTAGAGSAAGSATTATATGCAATGCAAGCTGCATGTATT 7 1013 L4:28 TCACTAGAGSAAGSATTATATGCAATGCAAGCTVTCTGTATT 7 1014 L4:29 TWCACTTTAGGTTGCGYATTGCTCGATCAAGAGTTGCAAGTC 8 1015 L4:30 TWCACTTTAGGTTGCGYATTGCTCGATCGTGAGTTGCAAGTC 8 1016 L4:31 GCTAAAGAAGAAAGGGAAACACCTCAAACTGATAGTATGYCT 9 1017 L4:32 GCTAAAGAAGAAAGGGAAACACCTACTACTGATAGTATGYCT 9 1018 L4:33 CCATTAWTKCGACAAGCTTTGAATTTAAAGGATCACCAARGC 10 1019 L4:34 CCATTAWTKCGACAAGCTTTGGAWTTAAAGGATCACCAARGC 10 1020 L4:35 GCAGRWCCAGCCTTCTTATTCGKGVTTGAATTGVTKATATGC 11 1021 L4:36 GGAHTTGAAAAACAACTTAAATGTGAAAGTGGGTCTTAA 12 1022 L4:37 GGAGCTGAAAAACAACTTAAATGTGAAAGTGGGTCTTAA 12 1023 L4:38 TYTATCGAGCATCTCAATGGCCAWGGCGTCCAWCAGAGCTCG 13 1024 L4:39 MTCATCGAGCATCTCAATGGCCAWGGCGTCCAWCAGAGCTCG 13 1025 L4:40 TYTATCGAGCATCTCAATGGCCAWGGCGTCCAWCAGAGCGCB 13 1026 L4:41 MTCATCGAGCATCTCAATGGCCAWGGCGTCCAWCAGAGCGCB 13 1027 L4:42 TTGCCAGCTWKCCCCTTCTAAGRGGCAAAAGTGAGTGGCGTG 14 1028 L4:43 CCTCCAGCTWKCCCCTTCTAAGRGGCAAAAGTGAGTGGCGTG 14 1029 L4:44 AKCCCAGCTWKCCCCTTCTAAGRGGCAAAAGTGAGTGGCGTG 14 1030 L4:45 TAAAGCACDTCTCATAYTTTTTGCGTTATTACGAAVAAAATC 15 1031 L4:46 TAAAGCACDTCTCATTSCTTTTGCGTTATTACGAAVAAAATC 15 1032 L4:47 TAAAGCACDTCTCATAYTTTTAYTGTTATTACGAAVAAAATC 15 1033 L4:48 TAAAGCACDTCTCATTSCTTTAYTGTTATTACGAAVAAAATC 15 1034 L4:49 TCCTGTCCYGGAGCATACTYTTGCTSCATCGCGGTRACTTAG 16 1035 L4:50 TCCTGTCCYGAKGCATACTYTTGCTSCATCGCGGTRACTTAG 16 1036 L4:51 GGCAABTGAATTKTCAGCAGTTTCAAMTTGTTTTTCTGTAAA 17 1037 L4:52 GGCAABTGAATTCCTAGCAGTTTCAAMTTGTTTTTCTGTAAA 17 1038 L4:53 GGCAABTGAATTKTCAGCAGTTTCGTATTGTTTTTCTGTAAA 17 1039 L4:54 GGCAABTGAATTCCTAGCAGTTTCGTATTGTTTTTCTGTAAA 17 1040 L4:55 GGCAABTGAATTKTCAGCAGTTTCAAMATKTTTTTCTGTAAA 17 1041 L4:56 GGCAABTGAATTCCTAGCAGTTTCAAMATKTTTTTCTGTAAA 17 1042 L4:57 GGCAABTGAATTKTCAGCAGTTTCGTAATKTTTTTCTGTAAA 17 1043 L4:58 GGCAABTGAATTCCTAGCAGTTTCGTAATKTTTTTCTGTAAA 17 1044 L4:59 ATATAATSCGTBCTCTAGTGAMAAACCTTGTTGGCACAKAAA 18 1045 L4:60 ATATAATSCTTSCTCTAGTGAMAAACCTTGTTGGCACAKAAA 18 1046 L4:61 ATATAATSCGTBCTCTAGTGAMAAACCTTGTTGGCAGTAAAA 18 1047 L4:62 ATATAATSCTTSCTCTAGTGAMAAACCTTGTTGGCAGTAAAA 18 1048 L4:63 CAATRCGCAACCTAAAGTGWAAATACATGCAGCTTGCATTGC 19 1049 L4:64 CAATRCGCAACCTAAAGTGWAAATACAGABAGCTTGCATTGC 19 1050 L4:65 TGTTTCCCTTTCTTCTTTAGCGACTTGCAACTCTTGATCGAG 20 1051 L4:66 TGTTTCCCTTTCTTCTTTAGCGACTTGCAACTCACGATCGAG 20 1052 L4:67 CAAAGCTTGTCGMAWTAATGGAGRCATACTATCAGTTTGAGG 21 1053 L4:68 CAAAGCTTGTCGMAWTAATGGAGRCATACTATCAGTAGTAGG 21 1054 L4:69 GAATAAGAAGGCTGGWYCTGCGCYTTGGTGATCCTTTAAATT 22 1055 L4:70 GAATAAGAAGGCTGGWYCTGCGCYTTGGTGATCCTTTAAWTC 22 1056 L4:71 TTTAAGTTGTTTTTCAADTCCGCATATMABCAATTCAABCMC 23 1057 L4:72 TTTAAGTTGTTTTTCAGCTCCGCATATMABCAATTCAABCMC 23 1058 L1:50 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCACA 24 1059

TABLE 13 Oligo Sequence SEQ ID L1-9:01 TATTGGCATGTAAAGAATAAGCGTGCTCTGTTGGAC 1060 GCCCTG L1-9:02 GCCATTGAGATGCTCGATCGTCACGCCACTCACTTT 1061 TGCCCT L1-9:03 TTAGAAGGGGAAAGCTGGCAAGATTTTCTCCGTAAT 1062 AATGCA L1-9:04 AAATCAATGAGATGCGCTTTACTAAGTCATCGCGAT 1063 GGGGCA L1-9:05 AAGGTATGTCTTGGTACAGGATTCACAGAAAAACAG 1064 TACGAA L1-9:06 ACTGCTGAAAATAGTTTGGCCTTTCTGTGCCAACAA 1065 GGTTTC L1-9:07 TCACTAGAGAATGCTTTATATGCAATGCAAGCTGTC 1066 TGTATC L1-9:08 TTCACTTTAGGTTGCGTTTTGCTGGATCAAGAGCTC 1067 CAAGTC L1-9:09 GCTAAAGAAGAAAGGGAAACACCTACTACTGATAGT 1068 ATGCCC L1-9:10 CCATTATTGCGACAAGCTTTGGAATTAAAAGATCAC 1069 CAAGGG L1-9:11 GCAGAGCCAGCCTTCTTATTCGGATTGGAATTGATA 1070 ATATGC L1-9:12 GGATTGGAAAAACAACTTAAATGTGAAAGTGGGTCT 1071 TAA L1-9:13 ACGATCGAGCATCTCAATGGCCAGGGCGTCCAACAG 1072 AGCACG L1-9:14 TTGCCAGCTTTCCCCTTCTAAAGGGCAAAAGTGAGT 1073 GGCGTG L1-9:15 TAAAGCGCATCTCATTGATTTTGCATTATTACGGAG 1074 AAAATC L1-9:16 TCCTGTACCAAGACATACCTTTGCCCCATCGCGATG 1075 ACTTAG L1-9:17 GGCCAAACTATTTTCAGCAGTTTCGTACTGTTTTTC 1076 TGTGAA L1-9:18 ATATAAAGCATTCTCTAGTGAGAAACCTTGTTGGCA 1077 CAGAAA L1-9:19 CAAAACGCAACCTAAAGTGAAGATACAGACAGCTTG 1078 CATTGC L1-9:20 TGTTTCCCTTTCTTCTTTAGCGACTTGGAGCTCTTG 1079 ATCCAG L1-9:21 CAAAGCTTGTCGCAATAATGGGGGCATACTATCAGT 1080 AGTAGG L1-9:22 GAATAAGAAGGCTGGCTCTGCCCCTTGGTGATCTTT 1081 TAATTC L1-9:23 TTTAAGTTGTTTTTCCAATCCGCATATTATCAATTC 1082 CAATCC L1-9:24 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCACA 1083

The assembly reaction products were cloned into the pVER7314 backbone and transformed into tester strain E. coli KM3. To carry out library diversity analysis, DNA preps from 96 colonies grown on LB+Cb only (representing no repressor positive selection bias) were subjected to sequence analysis. These data showed approximately 30% of the clones recovered were unaltered L1-9 backbone and the remaining clones had approximately one to two targeted changes per clone. Additional non-targeted residue changes were recovered in the mutated population, either due to PCR errors or from poor quality oligonucleotides incorporated into the assembly reactions.

I. Library L4 Screening

Approximately 20,000 clones arising from the repressor prescreen were tested for activation by 0, 0.2 and 1 μg/ml concentrations of ethametsulfuron using the M9 assay plates. Surprisingly, over 100 hits were observed from the 0.2 μg/ml ethametsulfuron treatment. These putative hits were re-arrayed in 96-well format and re-tested for β-galactosidase induction by 0, 0.2 and 1 ppm ethametsulfuron using a liquid culture based assay system. FIG. 4 shows relative β-galactosidase activities of 45 exemplary putative library L4 hit clones 97-142 against 0, 0.2 and 1 ppm ethametsulfuron. Cultures grown in 96-well format were subcultured into fresh LB with inducer at the indicated concentration and grown overnight and then processed for the enzyme assay. For detection of induced activity, 5 μl of perforated cell mixture was used. For detection of background activity, 25 μl of cells were used such that detectable activity could be measured in the same time frame for all treatments. Background activity values were multiplied by ten to bring them into the range of the graph. The numbers below each sample refers to the library clone number. The latter part of the graph contains the controls 1st round hit L1-9 as well as wt TetR.

DNA sequences for all 142 putative hit clones were determined and the translated polypeptides aligned. After assigning each polypeptide in the alignment with a relative ethametsulfuron response, patterns of amino acid incorporation at varied or mutated residues associated with high or low response activity and high or low uninduced activity were identified. The most significant findings from this analysis were: C138G or L170V mutations were heavily favored in the top clones L4-59, -89, -110, -116, -118, -120, -124, -129, -133, -139, -140 and -142; and K108 Q was heavily incorporated in clones with the highest activity at the lowest dose of 0.2 ppm, but these clones showed somewhat leaky background (e.g., L4-98, -106, -113, -126, -130, and -141). Results from clone L4-18 having the K108Q shows another possible interesting mutation of L55M. This clone is induced to a high level with 0.2 ppm Es, but does not show the associated high background activity typically observed for K108Q-containing clones. The L55M mutation may have increased repressor activity. It is of interest that none of these changes other than L55M were designed diversity—all were derived from false incorporation of nucleotides during library assembly and few of these changes were represented in the unselected clone population.

J. Third Round Library Designs and Screening

Library L6: Shuffling for Enhanced Chlorsulfuron Response

Since clones L2-14 and L2-18 had the best chlorsulfuron activity profile from library L2, their amino acid diversity was used as the basis for the next round of shuffling. In addition to the diversity provided by these backbone sequences, additional residue changes thought to enhance packing of chlorsulfuron based on the 3D model predictions were included. New amino acid positions targeted were 67, 109, 112 and 173 (see, Table 14). Substitution of Gln (Q) at position 108 and Val (V) at position 170 were shown to likely be important changes in library L4 for gaining enhanced SU responsiveness and so were varied here as well. A summary of the diversity chose is shown in Table 14. The oligonucleotides designed and used to generate library 6 are shown in Table 15.

Library L6 was assembled, rescued, ligated into pVER7314, transformed into E. coli KM3 and plated out onto LB carbenicillin/kanamycin, and carbenicillin only control media as before. Library plates were then picked into 42 384-well microtiter plates (˜16,000 clones) containing 60 μl LB carbenicillin (Cb) broth per well. After overnight growth at 37° C. the cultures were stamped onto M9 assay plates containing no inducer, 0.2 ppm, and 2.0 ppm chlorsulfuron as test inducer. Following incubation at 30° C. for ˜48 hrs, putative hits responding to chlorsulfuron treatment as determined by increased blue colony color were re-arrayed into six 96-well microtiter plates and used to stamp a fresh set of M9 assay plates to confirm the above results. For a more detailed analysis of the relative induction by chlorsulfuron, digital photographs were taken of the plates after various time points of incubation at 30° C. and colony color intensity measured using the digital image analysis freeware program ImageJ (Rasband, US National Institutes of Health, Bethesda, Md., USA, rsb.info.nih.gov/ij/, 1997-2007). Using these results enabled ranking of clones in multiplex format by background activity (no inducer), activation with low or high level inducer application (blue color with inducer), and fold activation (activation divided by background). Activation studies using 0.2 μg/ml chlorsulfuron as inducer for the top set of clones shows an approximately 3 fold improvement in activation while obtaining lower uninduced levels of expression (Table 12). In addition to this analysis, DNA sequence information for most clones (490 clones) was obtained and the deduced polypeptides aligned with each other as well as with their corresponding activity information. From this analysis sequence-activity relationships were derived (Table 12). Residues biased for improved activity are indicated in larger bold type. Briefly, C at position 100, and Q at positions 108 and 109 strongly correlated with activation, while R at position 138, L at position 170, and A or G at position 173 were highly preferred in clones with the lowest background activity. Though some positions were strongly biased, i.e., observed more frequently in the selected population, the entirety of introduced diversity was observed in the full hit population. This information will aid in the design of further libraries to improve responsiveness to chlorsulfuron.

TABLE 14 Sequence Amino acid residue position Name 60 64 67 82 86 100 105 108 109 112 113 116 134 138 139 147 Library A M N C Q M S M M G N Diversity Q Y T W K L T Q V R V F Q A L H G I V wt reference L H F N F H P K Q T L Q L G H E L2-14 M A F N M C W K Q T A M V R V F L2-18 M Q F T M W W K Q T A Q M R N F L6-1B03 M A I N M C W Q Q A A M V R V F L6-2C09 M Q Y T M C W Q L T A Q M R V F L6-2D07 M Q F T M C W Q Q T A M M R V F L6-3H02 M A Y T M C W Q H S A M V R V F L6-4D10 M Q Y N M C W K Q S A M V R V F L6-5F05 M A I N M C W Q Q A A Q V R V F L6-5G06 M Q Y N M C W Q Q T A Q V R V F L6-5H06 M Q I N M C W K Q T A M V R V F L6-5H12 M A Y N M C W K Q T A Q M R V F L6-6F07 M A L T M C W Q Q S A M M R V F Bias in top none Y N C Q Q none none V R V population Sequence Amino acid residue positiion Name 151 164 170 173 174 177 178 Library S L G L 0.2 ppm Control 0.2 ppm Diversity L A A W 48 hr 84 hr 48 hr/ V V Control 84 hr wt reference H D L A I F D  5.2 5.3 1.0 L2-14 S A L A L K D 11.8 6.6 1.8 L2-18 L A L A W K D  5.9 5.7 1.0 L6-1B03 S A L A W K D 30.0 6.6 4.6 L6-2C09 L A L A W K D 13.6 5.2 2.6 L6-2D07 S A V A W K D 20.0 5.8 3.4 L6-3H02 S A V A W K V 15.8 5.6 2.8 L6-4D10 S A L A W K D 18.4 5.0 3.7 L6-5F05 L A L A W K D 22.0 5.4 4.1 L6-5G06 L A L G W K D 34.4 7.0 4.9 L6-5H06 L A V A W K D 13.7 5.1 2.7 L6-5H12 L A V A W K D 23.7 5.7 4.2 L6-6F07 S A L A W K D 11.6 5.1 2.3 Bias in top none L A/G W D population

TABLE 15 Oligo Sequence SEQ ID L6:1 TATTGGCATGTAAAAAATAAGCGAGCTCTGCTCGACG 1084 CCTTA L6:2 GCAGAGCCAGCCTTCTTATTCGGCCTTGAATTGATCA 1085 TATGC L6:3 ATATAATGCATTCTCTAGTGAAAAACCTTGTTGGCAT 1086 AAAAA L6:4 TTTAAGTTGTTTTTCTAATCCGCATATGATCAATTCA 1087 AGGCC L6:5 TTAGAAGGGGAAAGCTGGCAAGATTTTTTACGTAATA 1088 MTGCT L6:6 TAAAGCACATCTCATACTTTTAGCAKTATTACGTAAA 1089 AAATC L6:7 TTGCCAGCTTTCCCCTTCTAAAGGGCAMAHGTGAGTT 1090 GCGTG L6:8 TTGCCAGCTTTCCCCTTCTAAAGGGCAATAGTGAGTT 1091 GCGTG L6:9 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCCTTT 1092 AATTC L6:10 GCCATTGAGATGATGGATAGGCACGCAACTCACTATT 1093 GCCCT L6:11 RSTGCTGAAAATATGTTAGCCTTTTTATGCCAACAAG 1094 GTTTT L6:12 TTTACTTTAGGTTGCGTATTGTTTGATCAAGAGCTCC 1095 AAGTC L6:13 TGTTTCCCTTTCTTCTTTAGCGACTTGGAGCTCTTGA 1096 TCAAA L6:14 GCCATTGAGATGATGGATAGGCACGCAACTCACDTKT 1097 GCCCT L6:15 GCCATTGAGATGATGGATAGGCACCAAACTCACDTKT 1098 GCCCT L6:16 GCCATTGAGATGATGGATAGGCACCAAACTCACTATT 1099 GCCCT L6:17 AAAAGTATGAGATGTGCTTTACTAAGCCATCGCGATG 1100 GAGCA L6:18 AAAGTATGKTTAGGTACACGCTGGACAGAAMAACAWT 1101 ATGAA L6:19 AAAGTATGKTTAGGTACACGCTGGACAGAAMAAWTGT 1102 ATGAA L6:20 RSTGCTGAAAATCAATTAGCCTTTTTATGCCAACAAG 1103 GTTTT L6:21 TCACTAGAGAATGCATTATATGCARTGAGTGCGTGGR 1104 GGGTG L6:22 TCACTAGAGAATGCATTATATGCARTGAGTGCGTGGR 1105 GGAAC L6:23 TTTACTTTAGGTTGCGTATTGTTTGATCAAGAGAGCC 1106 AAGTC L6:24 GCTAAAGAAGAAAGGGAAACACCTACTACTGCTAGTA 1107 TGCCG L6:25 CCATTAKTGCGACAAGBTTKGGAATTAAAGGATCACC 1108 AAGGT L6:26 CCATTAGCCCGACAAGBTTKGGAATTAAAGGATCACC 1109 AAGGT L6:27 GGATTAGAAAAACAACTTAAATGCGAAAGTGGGTCTT 1110 AA L6:28 CCTATCCATCATCTCAATGGCTAAGGCGTCGAGCAGA 1111 GCTCG L6:29 TTGCCAGCTTTCCCCTTCTAAAGGGCAMAHGTGAGTT 1112 TGGTG L6:30 TTGCCAGCTTTCCCCTTCTAAAGGGCAATAGTGAGTT 1113 TGGTG L6:31 GCGTGTACCTAAMCATACTTTTGCTCCATCGCGATGG 1114 CTTAG L6:32 GGCTAACATATTTTCAGCASYTTCATAWTGTTKTTCT 1115 GTCCA L6:33 GGCTAATTGATTTTCAGCASYTTCATAWTGTTKTTCT 1116 GTCCA L6:34 GGCTAACATATTTTCAGCASYTTCATACAWTTKTTCT 1117 GTCCA L6:35 GGCTAATTGATTTTCAGCASYTTCATACAWTTKTTCT 1118 GTCCA L6:36 CAATACGCAACCTAAAGTAAACACCCYCACAGCACTC 1119 AYTGC L6:37 CAATACGCAACCTAAAGTAAAGTTCCYCACAGCACTC 1120 AYTGC L6:38 TGTTTCCCTTTCTTCTTTAGCGACTTGGCTCTCTTGA 1121 TCAAA L6:39 CMAAVCTTGTCGCAMTAATGGCGGCATACTAGCAGTA 1122 GTAGG L6:40 CMAAVCTTGTCGGGCTAATGGCGGCATACTAGCAGTA 1123 GTAGG L6:41 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCGCA 1124 K. Library L7: Shuffling for Enhanced Ethametsulfuron Response

The choice of parents to represent the amino acid residue diversity for library L7 was based on the conclusions of library L4 analysis—namely incorporation of mutations K108Q, C138G and L170V. Clones were also chosen to bring in other changes that occurred at a much lower frequency in L4, but may have been contributing to activity. These residues are L55M, N129H, V137A and F140Y. In addition to family diversity, other residue modifications were introduced at amino acid positions 67, 109, 112, 117, 131 and 173 based on structural modeling. This information is summarized in Table 14 showing L7 diversity summary. Also shown in Table 16 is a sequence alignment the top 10 performing L7 hits limited to the differences between the hits and wt TetR. Activity was determined using image analysis of colony color (ImageJ software) on M9 assay plates containing 0, 0.02 or 0.2 ppm ethametsulfuron. At the bottom of Table 16 is a summary of the sequence-activity relationship analysis for the entire data set derived from more than 300 clones, with the strongly biased positions shown in larger bolded type. Even though some positions were strongly biased, i.e., observed more frequently in the selected population, e.g., M at position 55, the entirety of introduced diversity was observed in the full hit population.

TABLE 16 Amino acid residue position Sequence 55 64 67 85 86 100 104 105 108 109 112 113 116 117 129 131 134 135 137 138 139 140 147 151 170 173 174 177 wt L H F S F H R P K Q T L Q L N L L S V G H F E H L A I F reference L7 M M Q M S M N M A G F L G diversity L Y K L T L H L V C Y A A F Q A V V L H G V L7-1C03-A05 M A V I M C G F Q Q — A S — H — M Q A G I — L L V — L N L7-1C07-A06 M A Y — M C G F Q Q — A S — H — M Q A G I — L L V — L K L7-1F08-A11 M A Y — M C G F Q Q — A S — — — M Q — G I Y L L V — L K L7-1G06-B02 M A Y — M C G F Q Q — A S M — — M Q — G I Y L L V — L K L7-2C11-B11 M A Y — M C G F Q Q — A S M — M M Q A G I — L L V V L K L7-2D08-C02 M A Y — M C G F Q Q — A S — H — M Q — G I Y L L V — L K L7-3A10-C09 M A Y — M C G F Q Q — A S — H — M Q — G I Y L L V — L K L7-3C08-C10 M A Y — M C G F Q Q G A S M — M M Q A G I Y L L V — L K L7-3E03-D01 M A Y — M C G F Q Q — A S — H M M Q A G I Y L L V — L K L7-3E04-D02 M A Y — M C G F Q Q S A S — H M M Q A G I — L L V — L K Bias in top M Y Q Q N G V population

The L7 library was constructed as for Library L1 using the set of oligonucleotides shown below in Table 17.

TABLE 17 Oligo SEQ ID Oligo sequence ID L7:01 TATTGGCATGTAAAAAATAAGCGAGCTCTGCTCGACGCA 1125 WTG L7:02 GCCATTGAGATGCTGGATAGGCACGCGACTCACDTSTGC 1126 CCT L7:03 GCCATTGAGATGCTGGATAGGCACGCGACTCACTATTGC 1127 CCT L7:04 TTAGAAGGGGAAAGCTGGCAAGATTTTTTACGTAATAAC 1128 GCT L7:05 AAAAGTATGAGATGTGCTTTACTAAGTCATCGCGATGGA 1129 GCA L7:06 AAAGTATGTTTAGGTACAGGCTTTACAGAAMAGMTGTAT 1130 GAA L7:07 AAAGTATGTTTAGGTACAGGCTTTACAGAAMAGCAMTAT 1131 GAA L7:08 RSTGCCGAAAATAGTMTGGCCTTTTTATGCCAACAAGGT 1132 TTT L7:09 TCACTAGAGMACGCAMTGTATGCAATGCAGGCTGYTKGT 1133 ATT L7:10 TWTACTTTAGGTTGCGTATTGTTGGATCAAGAGCTTCAA 1134 GTC L7:11 GCTAAAGAAGAAAGGGAAACACCTACTACTGATAGTATG 1135 CCG L7:12 CCATTAGCTCGACAAGBTCTGGAATTAAAGGATCACCAA 1136 GGT L7:13 CCATTASTCCGACAAGBTCTGGAATTAAAGGATCACCAA 1137 GGT L7:14 GCAGAGCCAGCCTTCTTATTCGGCCTTGAATTGATCATA 1138 TGC L7:15 GGATTAGAAAAACAACTTAAATGTGAAAGTGGGTCTTAA 1139 L7:16 CCTATCCAGCATCTCAATGGCCAWTGCGTCGAGCAGAGC 1140 TCG L7:17 TTGCCAGCTTTCCCCTTCTAAAGGGCASAHGTGAGTCGC 1141 GTG L7:18 TTGCCAGCTTTCCCCTTCTAAAGGGCAATAGTGAGTCGC 1142 GTG L7:19 TAAAGCACATCTCATACTTTTAGCGTTATTACGTAAAAA 1143 ATC L7:20 GCCTGTACCTAAACATACTTTTGCTCCATCGCGATGACT 1144 TAG L7:21 GGCCAKACTATTTTCGGCASYTTCATACAKCTKTTCTGT 1145 AAA L7:22 GGCCAKACTATTTTCGGCASYTTCATAKTGCTKTTCTGT 1146 AAA L7:23 ATACAKTGCGTKCTCTAGTGAAAAACCTTGTTGGCATAA 1147 AAA L7:24 CAATACGCAACCTAAAGTAWAAATACMARCAGCCTGCAT 1148 TGC L7:25 TGTTTCCCTTTCTTCTTTAGCGACTTGAAGCTCTTGATC 1149 CAA L7:26 CAGAVCTTGTCGAGCTAATGGCGGCATACTATCAGTAGT 1150 AGG L7:27 CAGAVCTTGTCGGASTAATGGCGGCATACTATCAGTAGT 1151 AGG L7:28 GAATAAGAAGGCTGGCTCTGCACCTTGGTGATCCTTTAA 1152 TTC L7:29 TTTAAGTTGTTTTTCTAATCCGCATATGATCAATTCAAG 1153 GCC L7:30 GGGAACTTCGGCGCGCCTTAAGACCCACTTTCACA 1154

After transformation of the library into E. coli KM3 and plating on LB+Cb+Km the resulting colonies were reformatted into fifty-two 384-well microtiter plates (˜20,000 colonies) and subsequently used to replica plate onto M9 assay medium containing either 0 μg/ml, 0.02 μg/ml or 0.2 μg/ml ethametsulfuron. After incubation at 30° C. for 48 hrs the plates were observed and 326 hits responding to 0.02 μg/ml inducer were identified and re-arrayed into 96-well format. Following incubation at 30° C. for 15, 24, 48 and 120 hours, digital images of the plates were taken and the relative colony color information converted to numerical data. DNA sequence analysis was carried out in parallel, and the two data sets merged for calculation of sequence-activity relationships. Sequence data for the top ten clones as well as the summary of the sequence-activity relationships are shown in Table 16. The results of sequence-activity relationship study revealed preferences impacting both activation and background activities of the putative ethametsulfuron repressors (EsR's). For example, one significant finding from this library was that modification L55M greatly reduced background activity and thus enhanced levels of fold activation. As seen from libraries L4 and L6, K108Q and wt Q109 were preferred for activation. There was also a high degree of bias towards L170V related to activation. This is different from the L170A or L170G bias seen in library L6, as those modifications had a strong correlation with lowering background activity in library L6. Finally, having a less dramatic effect on activation but nevertheless preferred is F67Y.

L. Induction Properties of Top L7 Hits in Liquid Cultures

Based on the performance of the re-arrayed hits, a second re-array was done and the clones tested for β-galactosidase activity in liquid culture along with wt TetR controls and selected 2^(nd) round hits to further analyze their performance and shuffling progress. Top hits from the L7 library were re-arrayed and tested in 96-well culture format for relative induction by 0.02 and 0.2 ug/ml inducer or background activity without inducer (FIG. 5). Cultures were grown overnight and then subcultured into fresh medium containing appropriate treatments. Following six hours of incubation the cells were processed for enzyme assay. For assay of induced activity 5 μl of perforated cell mixture was used, for background activity 25 μl of cells were used such that detectable activity could be measured in the same time frame for all treatments. Background activity values were multiplied by ten to bring them into the range of the graph. The numbers below each sample refers to the final re-array well ID (vertical writing) and original re-array well ID (horizontal writing). The latter part of the graph contains the controls. Shown are 2nd round hits L4-89 and L4-120 as well as wt TetR. The final sample shows a control comprising wt TetR with 0.4 μM atc as cognate inducer for comparison. Results show that ten to fifteen of the top hits have induced activity approaching that of wt TetR induced with 0.4 μM atc. In addition, many of the hits have background activities nearly as low as wild type TetR. Some of the best hits have induction ratios with 0.2 ppm inducer (0.5 μM) approaching 70-80% of that of wt TetR (˜1200-fold). It is interesting that the hits performing best at the low inducer concentration of 0.02 ppm (50 nM) also tended to have the higher background activity indicating that they are less tightly bound to tet operator and more easily released with transient inducer binding.

Comparison of induction activity between the 2^(nd) and 3^(rd) round hits is striking, showing greater than 200-fold improvement. Considering this improvement, a single additional round of shuffling and screening may yield sulfonylurea repressors (SuRs) that are nearly as sensitive to ethametsulfuron as the wt TetR is for tetracycline.

Summary

FIG. 9 provides a cumulative summary of the introduced diversity and observed amino acids in active SuRs obtained from the screening assays. Even though some positions were strongly biased i.e., observed more frequently in the selected population, as indicated by larger bolded type, the entirety of introduced diversity was observed in the full hit populations.

M. Novel Diversity Through In Vitro Mutagenesis

Residues A64, M86, C100, G104, F105, Q108, A113, S116, M134, Q135, I139, Y140, L147, L151, V170, L174, and K177 of round 3 hit L7-A11 were each mutagenized to all possible 20 amino acids to generate a set of 340 clones. Each of the clones was replica plated onto M9 assay medium containing 0, 5, 20 and 200 ppb ethametsulfuron. To assess relative activity of each of the mutants the plates containing ligand were photographed following 18 hrs of incubation at 37° C. To determine leakiness of the repressor clones the plate having no ligand addition was photographed after incubation for 24 hrs at 37° C. followed by 48 hrs of incubation at 25° C. Quantitative measurements were made by scanning digital photographs of each colony for blue color using ImageJ software.

These data revealed that select substitutions at positions L60, A64, N82, M86, A113, S116, M134, L174, and K177 demonstrated an increase in ethametsulfuron sensitivity relative to the parent clone L7-A11.

N. Fifth-Round Shuffling

Shuffling designed for improved ethametsulfuron sensitivity was performed. Library L13 (Table 18) was designed to incorporate novel diversity generated by the in vitro mutagenesis experiment in Example 1M that had either positive or neutral effect on activity. In addition, the library also incorporated diversity at selected cysteine residues in the backbone as listed (Table 18). The predicted library size is 124,000 members.

TABLE 18 Library L13 Residue 60 64 68 82 86 88 100 113 116 121 134 174 177 195 203 L7-A11 L A C N M C C A S C M L K C C Diversity L A L K M N C A S T M L K C C F D C R R A M C F I H S A K N W G F R Y

The library was assembled from synthetic oligonucleotides listed in Table 19 using methodology as described previously in this example.

TABLE 19 Oligo Sequence SEQ ID L13:1 TGGCACGTCAAGAACAAGCGAGCTCTGCTAGACGCTA 1159 TGGCC L13:2 ATTGAGATGTTSGATAGGCACAAGACCCACTACTGTC 1160 CTTTG L13:3 ATTGAGATGTTSGATAGGCACAAGACCCACTACCTGC 1161 CTTTG L13:4 ATTGAGATGTTSGATAGGCACGMCACCCACTACTGTC 1162 CTTTG L13:5 ATTGAGATGTTSGATAGGCACGMCACCCACTACCTGC 1163 CTTTG L13:6 GAAGGGGAAAGCTGGCAAGACTTCTTGAGGAACAATG 1164 CTAAG L13:7 GAAGGGGAAAGCTGGCAAGACTTCTTGAGGAACARGG 1165 CTAAG L13:8 TCCAKGAGAAATGCTTTGCTCAGTCACCGTGATGGAG 1166 CCAAG L13:9 GTCTGCCTAGGTACGGGCTTCACGGAGCAACAGTATG 1167 AAACT L13:10 GTCGCTCTAGGTACGGGCTTCACGGAGCAACAGTATG 1168 AAACT L13:11 GCTGAGAACTSKCTTGCCTTCCTGACACAACAAGGTT 1169 TCTCC L13:12 ATGGAGAACTSKCTTGCCTTCCTGACACAACAAGGTT 1170 TCTCC L13:13 CTTGAGAACGCCCTCTACGCATTTCAAGCTGTTGGGA 1171 TCTAC L13:14 CTTGAGAACGCCCTCTACGCAGGTCAAGCTGTTGGGA 1172 TCTAC L13:15 CTTGAGAACGCCCTCTACGCAATGCAAGCTGTTGGGA 1173 TCTAC L13:16 ACTCTGGGTTGCGTCTTGCTGGATCAAGAGCTGCAAG 1174 TCGCT L13:17 AAGGAGGAGAGGGAAACACCTACTACTGATAGTATGC 1175 CGCCA L13:18 CTGGTTCGACAAGCTTACGAACTCCACGATCACCAAG 1176 GTGCA L13:19 CTGGTTCGACAAGCTTACGAACTCARAGATCACCAAG 1177 GTGCA L13:20 CTGGTTCGACAAGCTHTCGAACTCCACGATCACCAAG 1178 GTGCA L13:21 CTGGTTCGACAAGCTHTCGAACTCARAGATCACCAAG 1179 GTGCA L13:22 GAGCCAGCCTTCCTGTTCGGCCTTGAACTGATCATAW 1180 GTGGA L13:23 TTGGAGAAGCAGCTGAAGTGTGAAAGTGGGTCTTAAT 1181 GATAG L13:24 TTGGAGAAGCAGCTGAAGGCAGAAAGTGGGTCTTAAT 1182 GATAG L13:25 GTGCCTATCSAACATCTCAATGGCCATAGCGTCTAGC 1183 AGAGC L13:26 GTCTTGCCAGCTTTCCCCTTCCAAAGGACAGTAGTGG 1184 GTCTT L13:27 GTCTTGCCAGCTTTCCCCTTCCAAAGGCAGGTAGTGG 1185 GTCTT L13:28 GTCTTGCCAGCTTTCCCCTTCCAAAGGACAGTAGTGG 1186 GTGKC L13:29 GTCTTGCCAGCTTTCCCCTTCCAAAGGCAGGTAGTGG 1187 GTGKC L13:30 GAGCAAAGCATTTCTCMTGGACTTAGCATTGTTCCTC 1188 AAGAA L13:31 GAGCAAAGCATTTCTCMTGGACTTAGCCYTGTTCCTC 1189 AAGAA L13:32 GAAGCCCGTACCTAGGCAGACCTTGGCTCCATCACGG 1190 TGACT L13:33 GAAGCCCGTACCTAGAGCGACCTTGGCTCCATCACGG 1191 TGACT L13:34 GAAGGCAAGMSAGTTCTCAGCAGTTTCATACTGTTGC 1192 TCCGT L13:35 GAAGGCAAGMSAGTTCTCCATAGTTTCATACTGTTGC 1193 TCCGT L13:36 TGCGTAGAGGGCGTTCTCAAGGGAGAAACCTTGTTGT 1194 GTCAG L13:37 CAGCAAGACGCAACCCAGAGTGTAGATCCCAACAGCT 1195 TGAAA L13:38 CAGCAAGACGCAACCCAGAGTGTAGATCCCAACAGCT 1196 TGACC L13:39 CAGCAAGACGCAACCCAGAGTGTAGATCCCAACAGCT 1197 TTGCAT L13:40 AGGTGTTTCCCTCTCCTCCTTAGCGACTTGCAGCTCT 1198 TGATC L13:41 TTCGTAAGCTTGTCGAACCAGTGGCGGCATACTATCA 1199 GTAGT L13:42 TTCGADAGCTTGTCGAACCAGTGGCGGCATACTATCA 1200 GTAGT L13:43 GCCGAACAGGAAGGCTGGCTCTGCACCTTGGTGATCG 1201 TGGAG L13:44 GCCGAACAGGAAGGCTGGCTCTGCACCTTGGTGATCT 1202 YTGAG L13:45 ACACTTCAGCTGCTTCTCCAATCCACWTATGATCAGT 1203 TCAAG L13:46 TGCCTTCAGCTGCTTCTCCAATCCACWTATGATCAGT 1204 TCAAG L13:47 GCGCCAAGGTACCTTCTGCAGCTATCATTAAGACCCA 1205 CTTTC

The assembled library was then cloned into pVER7571. This vector is the same as vector pVER7314 except for having a mutated ribosome binding site to reduce the amount of repressor produced per cell. This modification allows for more stringent assessment of repressor activity in the standard blue/white genetic plate assay, as well as in the liquid based whole cell quantitative β-galactosidase assay. Following plating of the library, approximately 5,000 clones were re-arrayed and replica plated onto M9 assay plates with no addition, or with 2 ppb ethametsulfuron plus 0.002% arabinose. Colonies responding the strongest with ethametsulfuron while remaining white without inducer were chosen as hits. One of the hits, L13-23, was found to be ˜3-fold improved over the round 3 parent L7-A11 and to have the best repressor activity within this comparison (FIG. 11). Sequence changes of the round 5 hit compared to parent molecule L7-A11 and wt TetR are shown in Table 20.

TABLE 20 Clone 55 60 64 67 68 82 86 88 100 104 105 108 113 116 121 134 135 139 140 147 151 170 174 177 195 203 wt L L H F C N F C H R P K L Q C L S H F E H L I F C C L7-A11 M — A Y — — M — C G F Q A S — M Q I Y L L V L K — — L13-1-09 M — A Y — K M N A G F Q M S T F Q I Y L L V Y K — A L13-2-23 M F A Y — K M N A G F Q A C T F Q I Y L L V Y K — — L13-2-24 M — K Y L — M N C G F Q A W T F Q I Y L L V L H S A

Example 2 Plant Assay Development

A. Nicotiana benthamiana Leaf Infiltration Assay:

An in planta transient assay system was desired to rapidly confirm functionality of candidate SU-responsive repressors in planta prior to testing in transgenic plants. Therefore, an Agrobacterium based leaf infiltration assay was developed to measure repression and derepression activities. The strategy employed is to infiltrate leaves with a mixture of reporter and effector (repressor) Agrobacterium strains such that reporter activity is reduced by ˜90% in the presence of the effector and then derepressed following treatment with inducer.

Two ethametsulfuron repressors, EsR A11 and EsR D01, were selected for testing in conjunction with a wild type TetR control for dose response to ethametsulfuron by transient expression in Nicotiana benthamiana leaves (FIG. 6). To this end, three test strains were derived by transformation of Agrobacterium tumefaciens EHA105 with three different T-DNA based vectors. Agrobacterium strains harboring binary vectors with a 35S::tetO-Renilla Luciferase reporter and dPCSV-tetR or -SuR effector variants were constructed. In addition to these tester cultures, an existing Agrobacterium strain harboring a dMMV-GFP T-DNA was added to the assay mixture to monitor the progression of Agrobacterium infection for sampling purposes.

To test the system for chemical switch activation, mixtures of tester Agrobacterium cultures containing 10% 35S::tetO-ReLuc reporter Agro, 10% dMMV-GFP Agro and 80% dPCSV-wt tetR Agro were infiltrated into N. benthamiana leaves and co-cultivated for 36 hours in the growth chamber. At this time the infiltrated leaves were excised and the petiole placed into water (negative control) or inducer at the test concentrations indicated in FIG. 6 and allowed to co-cultivate for another 36 hours. Infected leaf areas were assayed for Renilla luciferase activity and inducer treatments compared. The results show significant repression of reporter activity (˜90%) with no inducer treatment (water control) for all tested repressors, and significant but incomplete induction of the EsR D01 repressor at inducer concentration as low as 0.02 ppm Es. Both EsR's were fully induced at 0.2 ppm Es whereas TetR was only fully induced at 2.0 ppm anhydrotetracycline (atc) (FIG. 6).

B. High Throughput in Planta Assay Development Using N. tabacum BY-2 Cell Culture

In addition to the leaf assay it was desired to have an in planta assay to enable high throughput screening of SuR libraries for optimal plant functionality. We designed a system similar to the leaf assay but using tobacco BY-2 cell culture in 96-well format. BY-2 cell culture was transformed with a dMMV-HRA construct such that the culture would withstand treatment with target sulfonylurea test compounds. The resultant cell line grows and is fully resistant to 200 ppb chlorsulfuron.

Example 3 Operator Binding Assay

To confirm that sulfonylurea ligands were binding directly to the modified repressor molecules and causing derepression, an in vitro tet operator gel shift study was undertaken.

An electrophoretic gel mobility shift assay (EMSA) of EsR variants was done to monitor binding to the tet operator (tetO) sequence and response of the complex to inducers Es and Cs. TetO consists of a synthetic 48 by tetO-containing fragment created from hybridization of oligonucleotide tetO1 (SEQ ID NO: 1155): 5′-CCTAATTTTTGTTGACACTCTATCATTGATAGAGTTATTTTACCACTC-3′ and complementary oligonucleotide tetO2 (SEQ ID NO: 1156): 5′-GGATTAAAAACAACTGTGAGATAGTAACTATCTCAATAAAATGGTGAG-3′ The tet operator is shown in bold.

An oligonucleotide and its complement of the same size containing no palindromic sequence was used as a control (SEQ ID NO: 1157): 5′-CCTAATTTTTGTTGACTGTGTTAGTCCATAGCTGGTATTTTACCACTC-3′ and complementary oligonucleotide (SEQ ID NO: 1158): 5′-G GATTAAAAACAACTGACACAATCAGGTATCGACCATAAAATGGTGAG-3′

Five pmol of TetO or control DNA was mixed with the indicated amounts (FIG. 7) of ethametsulfuron repressor protein (L7A11) or BSA control with or without inducer in complex buffer containing 20 mM Tris-HCl (pH8.0) and 10 mM EDTA. The mixture was incubated at room temperature for 0.5 hour before loading onto the gel. The reaction was electrophoresed on a Novex 6% DNA retardation gel (Invitrogen, EC6365BOX) at room temperature, 38 V in 0.5×TBE buffer for about 2 hours. DNA was detected by ethidium bromide staining. The DNA size marker consists of the low DNA mass ladder (InVitrogen 10068-013).

The results are shown in FIG. 7. These results directly demonstrate that the modified repressors bind to operator DNA (lane 1 vs. lanes 3-5) and then are released from the operator sequence in an inducer-specific and dose dependent manner. The data also indicate an inducer preference for operator release by Es compared to Cs (lane 9 vs. 10). No change in operator release could be detected by atc compared to no inducer (lane 5 vs. 11).

Example 4 Binding and Dissociation Constants

Select SU repressors were further characterized for operator and ligand binding, affinity and dissociation kinetics using Biacore™ SPR technology (Biacore, GE Healthcare, USA). The technology is based on surface plasmon resonance (SPR), an optical phenomenon that enables detection of unlabeled interactants in real time. The SPR-based biosensors can be used in determination of active concentration, screening and characterization in terms of both affinity and kinetics.

The kinetics of an interaction, i.e., the rates of complex formation (k_(a)) and dissociation (k_(d)), can be determined from the information in a sensorgram. If binding occurs as sample passes over a prepared sensor surface, the response in the sensorgram increases. If equilibrium is reached, a constant signal is seen. Replacing the sample with buffer causes the bound molecules to dissociate and the response decreases. Biacore evaluation software generates the values of k_(a) and k_(d) by fitting the data to interaction models.

The affinity of an interaction is determined from the level of binding at equilibrium (seen as a constant signal) as a function of sample concentration. Affinity can also be determined from kinetic measurements. For a simple 1:1 interaction, the equilibrium constant K_(D) is the ratio of the kinetic rate constants, k_(d)/k_(a).

A. Operator Binding Characterization of Repressors

Repressor k_(a) (M⁻¹ s⁻¹) K_(d) (s⁻¹) K_(D) (nM) Wt TetR 3.3 × 10⁵ 3.0 × 10⁻³ 9.0 ± 1.0 L7-1C03-A5 4.7 × 10⁴ 7.8 × 10⁻³ 150 ± 5  L7-3E03-D1 5.5 × 10⁴ 1.1 × 10⁻² 200 ± 50  L7-1F08-A11 7.1 × 10⁴ 1.7 × 10⁻² 250 ± 120 L7-1G06-B2 4.6 × 10⁴ 1.9 × 10⁻² 430 ± 160 B. SU Binding Characterization of Repressors

KD (M) Repressor Es +Mg Es −Mg Cs +Mg Cs −Mg ATC +Mg L7-1C03-A5 0.46 1.78 83 365 Null L7-1F08-A11 0.45 1.09 40  92 Null L7-1G06-B2 0.53 2.15 60 255 Null L7-3E03-D1 0.73 2.15 48 115 Null Wt TetR Null Null Null Null 0.0036

Example 5 Sulfonylurea Repressor Ligand-Binding Domain Fusions

The ligand binding domains from the sulfonylurea repressors provided herein can be fused to alternative DNA binding domains in order to create further sulfonylurea repressors that selectively and specifically bind to other DNA sequences (e.g., Wharton and Ptashne (1985) Nature 316:601-605). Many domain swapping experiments have been published, demonstrating the breadth and flexibility of this approach. Generally, an operator binding domain or specific amino acid/operator contact residues from a different repressor system will be used, but other DNA binding domains can also be used. For example, a polynucleotide encoding a TetR(D)/SuR chimeric polypeptide consisting of the DNA binding domain from TetR(D) (e.g., amino acid residues 1-50) and ligand binding domain of a SuR residues (e.g., amino acid residues 51-208 from TetR(B) can be constructed using any standard molecular biology method or combination thereof, including restriction enzyme digestion and ligation, PCR, synthetic oligonucleotides, mutagenesis or recombinational cloning. For example, a polynucleotide encoding a SuR comprising a TetR(D)/SuR chimera can be constructed by PCR (Landt et al. (1990) Gene 96:125-128; Schnappinger et al. (1998) EMBO J 17:535-543) and cloned into a suitable expression cassette and vector. Any other TetOp binding domains can be substituted to produce a SuR that specifically binds to the cognate tet operator sequence.

In addition, mutant TetO^(c) binding domains from variant TetR's having suppressor activity on constitutive operator sequences (tetO-4C and tetO-6C) can be used (see, e.g., Helbl and Hillen (1998) J Mol Biol 276:313-318; and Helbl et al. (1998) J Mol Biol 276:319-324). Further, the polynucleotides encoding these DNA binding domains can be modified to change their operator binding properties. For example, the polynucleotides can be shuffled to enhance the binding strength or specificity to a wild type or modified tet operator sequence, or to select for specific binding to a new operator sequence.

Additional variants could be made by fusing an SuR repressor, or an SuR ligand binding domain to an activation domain. Such systems have been developed using Tet repressors. For example, one system converted a tet repressor to an activator via fusion of the repressor to a transcriptional transactivation domain such as herpes simplex virus VP16 and the tet repressor (tTA, Gossen and Bujard (1992) Proc Natl Acad Sci USA 89:5547-5551). The repressor fusion is used in conjunction with a minimal promoter which is activated in the absence of tetracycline by binding of tTA to tet operator sequences. Tetracycline inactivates the transactivator and inhibits transcription.

Example 6 Testing of Repressor Proteins in Soybean

Any transformation protocols, culture techniques, soybean source, and media, and molecular cloning techniques can be used with the compositions and methods.

A Transformation and Regeneration of Soybean (Glycine max)

Transgenic soybean lines are generated by the method of particle gun bombardment (Klein et al. Nature 327:70-73 (1987); U.S. Pat. No. 4,945,050) using a BIORAD Biolistic PDS1000/He instrument and either plasmid or fragment DNA. The following stock solutions and media are used for transformation and regeneration of soybean plants:

Stock Solutions:

-   Sulfate 100× Stock: 37.0 g MgSO4.7H2O, 1.69 g MnSO4.H2O, 0.86 g     ZnSO4.7H2O, 0.0025 g CuSO4.5H2O -   Halides 100× Stock: 30.0 g CaCl2.2H2O, 0.083 g KI, 0.0025 g     CoCl2.6H2O -   P, B, Mo 100× Stock: 18.5 g KH2PO4, 0.62 g H3BO3, 0.025 g     Na2MoO4.2H2O -   Fe EDTA 100× Stock: 3.724 g Na2EDTA, 2.784 g FeSO4.7H2O -   2,4-D Stock: 10 mg/mL 2,4-Dichlorophenoxyacetic acid -   B5 vitamins, 1000× Stock: 100.0 g myo-inositol, 1.0 g nicotinic     acid, 1.0 g pyridoxine HCl, 10 g thiamine.HCL.

Media (Per Liter):

-   SB199 Solid Medium: 1 package MS salts (Gibco/BRL, Cat. No.     11117-066), 1 mL B5 vitamins 1000× stock, 30 g Sucrose, 4 ml 2, 4-D     (40 mg/L final concentration), pH 7.0, 2 g Gelrite -   SB1 Solid Medium: 1 package MS salts (Gibco/BRL, Cat. No.     11117-066), 1 mL B5 vitamins 1000× stock, 31.5 g Glucose, 2 mL 2,     4-D (20 mg/L final concentration), pH 5.7, 8 g TC agar -   SB196: 10 mL of each of the above stock solutions 1-4, 1 mL B5     Vitamin stock, 0.463 g (NH4)2 SO4, 2.83 g KNO3, 1 mL 2,4 D stock, 1     g asparagine, 10 g sucrose, pH 5.7 SB71-4: Gamborg's B5 salts, 20 g     sucrose, 5 g TC agar, pH 5.7. -   SB103: 1 pk. Murashige & Skoog salts mixture, 1 mL B5 Vitamin stock,     750 mg MgCl2 hexahydrate, 60 g maltose, 2 g gelrite, pH 5.7. -   SB166: SB103 supplemented with 5 g per liter activated charcoal.     Soybean Embryogenic Suspension Culture Initiation:

Soybean cultures are initiated twice each month with 5-7 days between each initiation. Pods with immature seeds from available soybean plants 45-55 days after planting are picked, removed from their shells and placed into a sterilized magenta box. The soybean seeds are sterilized by shaking them for 15 min in a 5% Clorox solution with 1 drop of ivory soap (i.e., 95 mL of autoclaved distilled water plus 5 mL Clorox and 1 drop of soap, mixed well). Seeds are rinsed using 2 1-liter bottles of sterile distilled water and those less than 3 mm are placed on individual microscope slides. The small end of the seed is cut and the cotyledons pressed out of the seed coat. Cotyledons are transferred to plates containing SB199 medium (25-30 cotyledons per plate) for 2 weeks, then transferred to SB1 for 2-4 weeks. Plates are wrapped with fiber tape. After this time, secondary embryos are cut and placed into SB196 liquid media for 7 days.

Culture Conditions:

Soybean embryogenic suspension cultures (cv. Jack) are maintained in 50 mL liquid medium SB196 on a rotary shaker, 150 rpm, 26° C. with cool white fluorescent lights on 16:8 h day/night photoperiod at light intensity of 60-85 μE/m2/s. Cultures are subcultured every 7 days to two weeks by inoculating approximately 35 mg of tissue into 50 mL of fresh liquid SB196 (the preferred subculture interval is every 7 days).

Preparation of DNA for Bombardment:

In particle gun bombardment procedures it is possible to use purified intact plasmid DNA; or DNA fragments containing only the recombinant DNA expression cassette(s) of interest. For every seventeen bombardment transformations, 85 μL of suspension is prepared containing 1 to 90 picograms (pg) of plasmid DNA per base pair of each DNA plasmid. Both recombinant DNA plasmids are co-precipitated onto gold particles as follows. The DNAs in suspension are added to 50 μL of a 10-60 mg/mL 0.6 μm gold particle suspension and then combined with 50 μL CaCl2 (2.5 M) and 20 μL spermidine (0.1 M). The mixture is vortexed for 5 sec, spun in a microfuge for 5 sec, and the supernatant removed. The DNA coated particles are then washed once with 150 μL of 100% ethanol, vortexed and pelleted, then resuspended in 85 μL of anhydrous ethanol. Five μL of the DNA coated gold particles are then loaded on each macrocarrier disk.

Tissue Preparation and Bombardment with DNA:

Approximately 150 to 250 mg of two-week-old suspension culture is placed in an empty 60 mm×15 mm petri plate and the residual liquid removed from the tissue using a pipette. The tissue is placed about 3.5 inches away from the retaining screen and each plate of tissue is bombarded once. Membrane rupture pressure is set at 650 psi and the chamber is evacuated to −28 inches of Hg. Following bombardment, the tissue from each plate is divided between two flasks, placed back into liquid media, and cultured as described above.

Selection of Transformed Embryos and Plant Regeneration:

After bombardment, tissue from each bombarded plate is divided and placed into two flasks of SB196 liquid culture maintenance medium per plate of bombarded tissue. Seven days post bombardment, the liquid medium in each flask is replaced with fresh SB196 culture maintenance medium supplemented with 100 ng/ml selective agent (selection medium). Transformed soybean cells can be selected using a sulfonylurea (SU) compound such as 2 chloro N ((4 methoxy 6 methy 1,3,5 triazine 2 yl)aminocarbonyl)benzenesulfonamide (common names: DPX-W4189 and chlorsulfuron). Chlorsulfuron (Cs) is the active ingredient in the DuPont sulfonylurea herbicide, GLEAN®. The selection medium containing SU is replaced every two weeks for 6-8 weeks. After the 6-8 week selection period, islands of green, transformed tissue are observed growing from untransformed, necrotic embryogenic clusters. These putative transgenic events are isolated and kept in SB196 liquid medium with Cs at 100 ng/ml for another 2-6 weeks with media changes every 1-2 weeks to generate new, clonally propagated, transformed embryogenic suspension cultures. Embryos spend a total of around 8-12 weeks in contact with Cs. Suspension cultures are subcultured and maintained as clusters of immature embryos and also regenerated into whole plants by maturation and germination of individual somatic embryos.

Somatic embryos became suitable for germination after four weeks on maturation medium (1 week on SB166 followed by 3 weeks on SB103). They are then removed from the maturation medium and dried in empty petri dishes for up to seven days. The dried embryos are then planted in SB71 4 medium where they are allowed to germinate under the same light and temperature conditions as described above. Germinated embryos are transferred to potting medium and grown to maturity for seed production.

B. Vector Construction and Testing

Plasmids were made using standard procedures and from these plasmids DNA fragments were isolated using restriction endonucleases and agarose gel purification according to the protocol described in Example 6A. Each DNA fragment contained three cassettes. Cassette 1 is a reporter expression cassette; Cassette 2 is the repressor expression cassette; and, Cassette 3 is an expression cassette providing an HRA gene. The repressors tested in Cassette 2 are described in Table 21. The polynucleotides comprising the repressor coding region were synthesized to comprise plant preferred codons. In all cases Cassette 1 contained a 35S cauliflower mosaic virus promoter having three tet operators introduced near the TATA box (Gatz et al. (1992) Plant J 2:397-404 (3XOpT 35S)) driving expression of DsRed followed by the 35S cauliflower mosaic virus 3′ terminator region. In all cases cassette three contained the S-adenoyslmethionine synthase promoter followed by the HRA version of the acetolactase synthase (ALS) gene followed by the Glycine max ALS 3′ terminator. The HRA version of the ALS gene confers resistance to sulfonylurea herbicides. EF1A1 is the promoter of a soybean translation elongation factor EF1 alpha described in patent publication US20080313776.

TABLE 21 Fragment Fragment Repressor Repressor Fragment Name alias Cassette 2 alias SEQ ID SEQ ID PHP37586A CHSW004 EF1A1::EsR1::Nos3′ L7-IC3-A5 1240 1222 PHP37587A CHSW005 EF1A1::EsR2::Nos3′ L7-1F8- 1241 1223 A11 PHP37588A CHSW006 EF1A1::EsR2::Nos3 L7-1G6- 1242 1224 B2 PHP37589A CHSW007 EF1A1::EsR4::Nos3′ L7-3E3- 1243 1225 D1 PHP39389A CHSW010 EF1A1::EsR5::CaMV35S3′ L12-1-10 1232 1226 PHP39390A CHSW011 EF1A1::EsR6::CaMV35S3′ L13-2-23 1233 1227

DNA fragments were used for soybean transformation according to the protocol described in Example 6A. Plants were regenerated and leaf discs (˜0.5 cm) were harvested from young leaves. The leaf discs were incubated in SB103 liquid media containing 0 ppm, 0.5 ppm or 5 ppm ethametsulfuron for 2-5 days. Ethametsulfuron (product number PS-2183) was purchased from Chem Service (West Chester, Pa.) and solubilized in either 10 mM NaOH or 10 mM NH₄OH. On each day leaf discs were examined under a dissecting microscope with a DsRed band pass filter. The presence of DsRed was scored visually.

Plants that expressed DsRed at 0 time were scored as leaky. Plants that did not express DsRed after five days were scored as negative. Plants that expressed DsRed after addition of ethametsulfuron were scored as inducible. Results from plants derived from DNAs described in Table 21 are shown in Table 22.

TABLE 22 Total % % Name Alias Events % Leaky Negative Inducible PHP37586A CHSW004 12 33 33 33 PHP37587A CHSW005 28 7 50 43 PHP37588A CHSW006 6 0 0 100 PHP37589A CHSW007 9 0 22 78 PHP39389A CHSW010* 19 5 26 42 PHP39390A CHSW011* 35 0 17 57 *In these cases the total does not equal 100% as multiple plants were examined from some events and, in some cases, different plants from the same event behaved differently.

This shows that the repressor protein responds to ethametsulfuron by inducing expression of DsRed. Plants derived from the first four fragments showed visual evidence of DsRed after three days of incubation. Plants derived from the last two fragments showed visual evidence of DsRed after two days of incubation. The presence of DsRed was scored visually, but this was confirmed by Western Blot analysis on a selection of transformants using a rabbit polyclonal antibody (ab41336) from Abcam (Cambridge, Mass.).

Leaf punches were harvested as described above from a selection of transformants and incubated in SB103 media with 0, 5, 50, 250 and 500 ppb ethametsulfuron. At all concentrations of ethametsulfuron, leaves showed visual evidence of DsRed after three days of incubation. At the lowest concentration (5 ppb) the presence of DsRed was limited to a “halo” near the outside edge of the leaf disc.

Plants were allowed to mature as described in Example 6A. Since soybeans are self fertilizing, the T1 seeds derived from these plants would be expected to segregate 1 wild type: 2 hemizyogote: 1 homozygote if only one transgene locus was created during transformation. Sixteen seeds from five different events were planted and allowed to germinate. Leaf punches were collected from young seedlings and incubated in SB103 media with 0 and 5 ppm ethametsulfuron. Leaf discs were scored for DsRed expression and 0 and 3 days and results are shown in Table 23.

TABLE 23 Total # Seeds # Germi- # Leaky # Negative Inducible Name Event ID nated Plants Plants Plants PHP37586A 6048.3.8.3 11 0 2 9 PHP37587A 6049.2.2.4 12 0 5 7 PHP37588A 6150.3.2.1 14 0 1 13 PHP37589A 6154.4.5.1 15 0 15 0 PHP39389A 6151.4.18.1 12 3 9 0

Example 7 Testing of Repressor Proteins in Corn

To evaluate SU repressors in plants, RFP reporter constructs were constructed and transformed into maize cells via Agrobacterium using the following T-DNA configuration:

-   RB-35S/TripleOp/Pro::RFP-Ubi Pro::EsR-HRA cassette-PAT cassette-LB.

Using standard molecular biology and cloning techniques, T-DNA vectors having the configuration above comprising selected round 3 SU repressors (EsRs) were constructed. The polynucleotides comprising the repressor coding region were synthesized to comprise plant preferred codons. The constructs are summarized below:

Construct ID SU repressor alias (EsR) SU repressor SEQ ID PHP37707 L7-1C3-A5 1240 PHP37708 L7-1F8-A11 1241 PHP37709 L7-1G6-B2 1242 PHP37710 L7-3E3-D1 1243

The reporter construct T-DNA contained a 35S promoter with two tet operators flanking the TATA box and one downstream adjacent to the transcription start site (as described by Gatz et al. (1992) Plant Cell 2:397-404) driving expression of the Red Fluorescent Protein gene, a ubiquitin driven SU repressor (EsR), an expression cassette containing the maize HRA gene for SU resistance and a moPAT expression cassette for selection.

Immature embryos were transformed using standard methods and media. Briefly, immature embryos were isolated from maize and contacted with a suspension of Agrobacterium, to transfer the T-DNA's containing the sulfonylurea expression cassette to at least one cell of at least one of the immature embryos. The immature embryos were immersed in an Agrobacterium suspension for the initiation of inoculation and cultured for seven days. The embryos were then transferred to culture medium containing carbinicillin to kill off any remaining Agrobacterium. Next, inoculated embryos were cultured on medium containing both carbinicillin and bialaphos (a selective agent) and growing transformed callus was recovered. The callus was then regenerated into plantlets on solid media before transferring to soil to produce mature plants. Approximately 10 single copy events from each of the constructs were sent to the greenhouse.

To evaluate de-repression, callus was transferred to medium with and without ethametsulfuron and chlorsulfuron and RFP Fluorescence was observed under the microscope (see FIG. 10A). Most events de-repressed and there were no obvious differences between the round three repressors tested. To evaluate de-repression in plants, seeds for single copy plants were germinated in the presence of ethamethsulfron and fluorescence was observed and photographed (see FIG. 10B). As a positive control, a vector containing the same configuration of expression cassettes as PHP37707-10, but with UBI::TetR in place of UBI::EsR, were transformed into maize immature embryos and tested for induction on doxycline. When grown in the presence of 1 mg/l doxycycline, transgenic callus and plants containing the TetR expression cassette induced over a similar 5-6 day period.

The articles “a” and “an” refer to one or more than one of the grammatical object of the article. By way of example, “an element” means one or more of the element. All book, journal, patent publications and grants mentioned in the specification are indicative of the level of those skilled in the art. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, certain changes and modifications may be practiced within the scope of the appended claims. These examples and descriptions are illustrative and are not read as limiting the scope of the appended claims. 

1. An isolated polypeptide comprising a sulfonylurea-responsive repressor that specifically binds to a polynucleotide comprising an operator sequence, wherein the binding is regulated by a sulfonylurea compound, wherein said polypeptide comprises an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 1240, wherein the sequence identity is determined over the full length of the polypeptide.
 2. The isolated polypeptide of claim 1, wherein the polypeptide is SEQ ID NO:
 1240. 